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INSECTS INJURIOUS TO THE HOP 
IN NEW YORK WITH SPECIAL REFERENCE 
TO THE HOP GRUB AND THE HOP REDBUG 



A THESIS 



PRESENTED TO 

THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY 

FOR THE DEGREE OF DOCTOR OF PHILOSOPHY 



BY 
IRA MYRON HAWLEY 



PUBLISHED AS CORNELL UNIVERSITY AGRICULTURAL 
EXPERIMENT STATION MEMIOR 15. NOVEMBER. 1918 



INSECTS INJURIOUS TO THE HOP 
IN NEW YORK WITH SPECIAL REFERENCE 
TO THE HOP GRUB AND THE HOP REDBUG 



A THESIS 



PRESENTED TO 

THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY 

FOR THE DEGREE OF DOCTOR OF PHILOSOPHY 



BY 

IRA MYRON HAWLEY 



PUBLISHED AS CORNELL UNIVERSITY AGRICULTURAL 
EXPERIMENT STATION MEMIOR 15, NOVEMBER, 1918 



A^^' 



CONTENTS 

EiGE 

Nature of the hop plant 147 

The hop-vine borer, or hop grub {Gortyna immanis Guente) 148 

Generic history 148 

Common names 149 

Distribution 149 

Hosts 149 

Financial loss caused 150 

Nature of the injury 150 

The work in the head of the hop 150 

The early ( inside) work in the N'ines 153 

The late (outside ) work on the v-ines 154 

The work in the roots 154 

The work of the young larva in grass 156 

Types of yards attacked 157 

Description of the species 159 

Life historj' and habits ,. 161 

Seasonal history 165 

Relation of climatic and soil conditions to seasonal history 166 

Natural enemies 166 

Control 169 

Experiments in 1914 171 

Experiments with carbon disulfid 174 

Experiments in 1915 176 

Experiments with carbon disulfid 176 

Experiments with poison bait 179 

Experiments ^ith para-dichlorobenzene 180 

Recommendations 181 

The hop redbug ( Paracalocoris hawleyi Knight) 182 

Nature of the injury 183 

Description of the species 184 

Life history and habits .- 186 

Seasonal history 188 

Natural enemies 188 

Predacious habit of the hop redbug 188 

Control 189 

The hop snout-nijth {Hypena humvli Harris) , 190 

Description 190 

Life history and habits 192 

Seasonal historj- 196 

Natural enemies 196 

Control 196 

The filamented looper ( Nematocampa limbata Haworth) 197 

Description 197 

Life history and habits 198 

Seasonal history 201 

Control 201 

The hop aphis ( Phorodon humvli Schrank) 202 

Seasonal history 202 

Nature of the injury 204 

Natural enemies 206 

Spraying and control experiments 206 

Recommendation 210 

143 



144 Contents 

PAGE 

The red wpider, or spider mite (Tetranychus telariua Linnaeus) 212 

C<.iitn)l 212 

TI»o hop iiu'rchfints (Poli/gonia intrrrognlinni.s Fabricius and P. comma Harris) 212 

lA'iif hopiK-rs ( Empoiuca fluwscews Fabricius and E. Jlaviscciis Inrdii Coding) 215 

aintrol 21G 

The milhpede (Julus caerideocinclus Wood) 210 

Thf It'iif minor [Agromyzn sp.) 210 

Flea IxTllfS ( I'si/lliixiis imiiclutnta MeLsh., and others) 217 

Lc'iif tdIIits (Archips romceana Harris and A. arffyrospila Walker) 21S 

M isc»-lliiin'<)us inaecte on hop 218 

Hiblio^raphy • 219 

Literature cited 223 



INSECTS INJURIOUS TO THE HOP IN NEW YORK 
WITH SPECIAL REFERENCE TO THE HOP GRUB AND THE HOP REDBUG 



INSECTS INJURIOUS TO THE HOP IN NEW YORK ' 

WITH SPECIAL REFERENCE TO THE HOP GRUB AND THE HOP REDBUG 

I. M. Hawley 

The investigations herein recorded were begun in the spring of 1913 
and continued in 1914 and 1915. The greater part of the time was spent 
in investigating the hop-virie borer (Gortyna immanis Guenee) and methods 
for controlling it. Two new pests, the hop redbug (Paracalocoris hawleyi 
Knight) and the filamented looper {Nematocam'pa limhata Haworth), 
were also studied, as well as an old but little-known pest, the hop snout- 
moth (Hypena humuli Harris). Some control experiments against the 
hop aphis (Phorodon humuli Schrank) under New York conditions were 
conducted, and notes were made on a few pests of lesser importance. 

NATURE OF THE HOP PLANT 

In order that the relation of these pests to their host plant may be 
clearly understood, a word should be said regarding the growth and 
characteristics of the hop. 

The growing of hops in the eastern United States is restricted to small 
sections of New York State, and for this reason the plant is little known. 
The hop is a perennial plant, the roots living over from year to year and 
sending up each spring a fresh supply of rapidly growing vines. There 
are several roots in each hop hill. The hills are from seven to eight feet 
apart and there are from seven to eight hundred in an acre. The vines 
must be twined around some sort of support, the commonest form being 
either poles alone or a series of poles and strings. In some cases two poles 
and no strings are used, but the commoner method is to have one pole 
to a hill, with strings running from the middle of each pole to the tops 
of the ones adjacent to it. 

In July and August the main vines send out arms, and on these the 
hops are borne. The flowers, or burs, are produced the latter part of 

• Also presented to the Faculty of the Graduate School of Cornell University, June, 1916, as a thesis 
in partial fultillinent of the requirements for the degree of doctor of philosophy. The work was done 
under the direction of Professor Glenn W. Herriclc. The drawings were made by Miss Anna C. Stryke. 

147 



148 



I. M HWVLKY 



July. :uhI the fiill-nrowii hops (fij?. 9) may In' picked from August 20 
to the middle of SeptemiuM-, dcptMidiiiji; on variety, weutlwr conditions, 
iuul inseet and fungous pests. After the hops are picked they are drjed 
and I»m1(m|. ;ind are then ready for market. 




Fig. 9. hops at ru king timk 

Most hops are used in fillinu; the demands of the breweries. Small 
oval bodies, known as lupulin p;ranules, are formed at the base of each 
bract, and these eontain resins whieh give the characteristic taste to the 
Ixjverages for which hops are used. 

THE HOP-VINE BORER. OR HOP GRUB 
(Gortyna imnuinis Ciuen(!'e) 



fJENERIC III.STORY 

1852 — Guen^, A.. Histoiro naturclle dea insectes 5 : 128 
Ig74 _GroU-. \. R., Buffal.) S«,c. Xat. Sci., Bui. 2: IS. 

1883 — Conwtc.ck. J. H., .Xmcr. iitir. 12 :'J7.') 

18H4 — Smith. J. B., V. S. Div. Knt.. Bii!. 4, o. 8. : 34 

1885 — LinttHT, .F. .\.. New York SUiU> Knt., Hopt.2:41 

1803 — Smith. J. B., V. S. Nat. Mm.. Bui. 44 : 175 

1897 — Howard. L. O., l'. S. Div. Knt., Bui. 7:40. 

1902 — Dyar. H. (;.. Lii«t N. /V. Ix-p.. p. 175 

1900 — Howard, I.. O., The hop, p. I'JS 

1910— Hamp«on. C. K., Cat. Up. Phul. «:41 

1917 — BarrivM, W., and .MclJunnougli, J., List Lt-p. Boriui .\i,„t 



Hydroecia 

Ciortyiia 

.Xpjiniea 

Hydroecia 

( lortyiia 

1 1 ydnii'cia 

Hydroecia 

(lortyiia 

( lortyna 

Hydroecia 

Clortvua 



Insects Injurious to the Hop in New York 149 

As may be seen from the preceding list, the generic name of Gortyna 
immanis has been changed many times by systematic workers on this 
group of noctuids. The reason for the changes has been the question 
ot the type of the genus. 

common names 

The common names apphed to Gortyna immanis are all based on the 
work of the larva. Dodge (1882) - gave the insect its first common name, 
the hop-vine borer; Comstock (1883) retained this name and added 
that of hop grub; Fletcher (1893 a) applied a third name, the collar- 
worm of the hop; and a fourth name, the hop-plant borer, was given by 
Howard (1897). Among hop growers the larvae are known as hop grubs, 
01- more commonly as grubs. 

distribution 

Gortyna immanis is a native North American insect and has been widely 
collected in the northern United States and in Canada (Howard, 1897). 
Smith (1884) gives for its cUstribution the northern United States from 
the Atlantic to the Pacific. The insect is especiall}^ abundant in the 
Eastern States and in Canada where hops are grown. In addition captured 
moths are reported from the States of Illinois, Colorado, and Washington 
(Howard, 1897). 

In spite of the fact that moths have been taken in the State of Washing- 
ton, no injury to the hop crop of the Pacific coast is reported in 
entomological literature. One popular article by Daniel Fhnt (1882) 
has been cjuoted as describing injury by the larva of tliis insect, but the 
writer of the present paper believes the work described is that of a boring 
beetle. The "worm" that did the damage does not conform to the char- 
acteristics of a lepidopterous larva. 

HOSTS 

So far as known, Gortyna immanis is able to reach maturity only on 
the hop. Evidence exists, however, supporting the possibiUty of other 
hosts. In the spring of 1914 a farmer near Waterville, New York, re- 
ported that he had occasionally found the young larvae at work in his 
corn. This report the writer was unable to verify at that time. Larvae 
placed on young corn plants in the spring of 1915 flourished until the 

2 Dates in parenthesis refer to Bibliuyraphy, page 219, or to Literature cited, page 223. 



150 I. M. Hawley 

plants wore killed. The work was similar to that on the hop during the 
early stages, when the larva bores inside the stem. 

In the spring of 1915 the young larvae were found very commonly 
breeding in gnu^s in and around hopyards. Their work on grass is very 
much like the early work on the hop, and is discussed at some length 
later (pjige I'A)). Cages were placed over five of these grass plants on 
June 7. On August 17 thvsv cages were examined, and no live larvae, 
pupae, or adults were to be found. It is assumed, therefore, that the 
larva cannot mature on grass. 

I INAN(I.\L LOSS CAUSED 

The lo.ss due to the work of the larva of (lortyna inimanis varies greatly 
in different years, and in different yards in any one year. In years when 
the insects are numerous there may result nearly a total loss to some 
growers. A hop grower in Bristol, New York, informed the writer that 
he had seen the ilamage so great that the hops were not picked. Dodge 
(1882) estimated the loss due to the insect in New York State in 1879 
at $000,(XK). 

The writer worked in one yard where there were ninety dead vines 
in one hundred hills, or a computable loss of twenty per cent from the 
work of the insect. To this must be added the damage in weakened 
vines. Judging from the hills ins|M>cted, this fiekl had not more than 
twenty-five hills ii) an acre in which the grubs had not worked. It is 
probal)le that a total loss of forty per cent would be a conservative estimate 
for this yard. 

NATUKE OF THi; INJURY 

The injury of (iorti/na iinni(tnis to the hop plant may l)e clas.sed under 
four phiuscs. depending on the part of the plant attacked: (1) the work 
in the head of the hop; (2) the early (inside) work in the vines; (3) the late 
(outside; work on the vines; (1) the work in the roots. 



4 



The work in the head of (he hop 

DfKJge (1882) and later writers on hop insects supposed that the egg 

of (i. immani.s was laid on the tip of tlie hop vine early in the spring. 

It was n*ix)rted that when the egg hatched, the young larva bored at 

once into the head, producing a blunted condition known as a muffle 



Insects Injurious to the Hop in New York 151 

head. As is explained later, this theory of egg laying is incorrect, but it 
is true that some of the young larvae do find their way into the head of 
the hop. 

Newly hatched larvae of G. immanis may crawl long distances and enter 
any part of the hop plant that is tender enough for their small mandibles, 
or jaws, to break open. Some of them in their journey reach the head 




Fig. 10. HEALTHY AND MUFFLE-HEADED HOP VINES. NATURAL SIZE 

The blunted condition of the injured heads on the right should be noted 
(Photograph by G. W. Herrick) 

of the hop and find a place for easy entrance in the budlike tip. There 
is no definite place or manner of entrance. Some larvae bore their way 
into the side of the head, leaving an easily recognizable hole; others enter 
the tip itself and make their way between the developing leaves; while 
a few enter the base of the head, or the vine just below the head, causing it 
to bend to one side. The vines attacked become stockier, and as the 



152 I. M. Hawley 

larva fotnls on the tondcr iiit< rior tissues, killing the growing point, the 
head usually takes on a short, thick shai)e with scraggly leaves, in con- 
trast to the pointed tip with closely folded leaves of a healthy head 

(fiR. 10). 

The root of a hop plant sends up fresh vines for a period of several 
weeks. The writer ha.s noteil caries in which, due to late hatching of the 




FlU. 11. ML>>LE-HEAUIiD HOP VINES RESll-TING FROM THE WUKK OK THE HOP-VINE 

BORER. REDUCED 

When the main bud is injured, the leaves and buds just below begin to develop 



i 



eggs, the heads of all the young shoots were completely riddled when 
early vines, then four feet u|) the poles, were free from injury. In 1915 
larvae were found in the hop heads when the yards were first inspected 
on May 0. At that time* the vines of the first lot were less than one 
foot high. ( )cc!i.si()nal inufTle heads could .still he found by the first of 
June, .\fter working in the tip of the lu)p for from one to two weeks, 
most of the larvae drop to the ground and join tho.se working in the vines. 



II 



Insects Injurious to the Hop in New York 



153 



The injury result inp; from the work of the larva in the heads is relatively 
small. The men who tie the hops choose the unaffected vines, and if 
by accident a muffle-headed vine is used it may be replaced at the next 
tying. When the head is killed, the two buds at the node just beneath 
it will grow rapidly (fig. 11), and occasionally one of the arms thus re- 
sulting is twined on the 
pole in place of the 
main vine. 

The early {inside) work 
in the vines 

In contradiction to 
earlier accounts, the 
writer has obtained evi- 
dence that many of the 
newly hatched larvae 
enter the hop vine 
at once, without first 
working in the hop 
heads. Most of the eggs 
hatch at a time when 
the vines are short and 
tender. The young 
larva enters usually 
near the surface of the 
ground — from two to 
four inches above the 
bed root. Only a small 
hole shows on the out- 
side, but at this point 
the vine breaks on bend- 
ing and the work of the young larva is found within. A discolored area 
running up or down the pithy center of the stem marks the course taken. 
The burrow is filled with wast6 material behind the little larva as it 
rapidly eats its way along (fig. 12). The larva grows, and sheds its skin 
at least twice before it is ready to eat its way from the vine, whose 
unyielding sides prevent further growth. 




Fig. 12. 



VINES CUT OPEN TO SHOW THE WORK OF THE 
HOP- VINE BORER. XU 



l.->4 1. M. 11 awi.p:y 

The newly hatched larva of (;. immaniK is loss than 2 millimotors long, 
but when roady to l('av(> the vinos it has roaohod a longth of from 8 to 
18 niilliniotoi-s. In lUlf) most of tho larvao were outsido the vines by 
June 9. In tho case of one hill («xaminod on that date, one Rriih was in 
a hop vino, one was in a blade of ^rass on the hill, and seven were working 
on the outside of tho vines. 

W hilo tho larviu^ work oftenor in young, tender shoot.s, they are .some- 
times found in tho bjisos of vinos that are well up tho polos. Occasionally 
they (Mitor a vine of this kind halfway to the tip, or from two to three 
feet above the ground. Sometimes a vino is found which has a muffle 
head and several larvae working in it at different points. All tliis 
strengthens the ovidonco that a larva, after crawling for some distance, 
enters wherever it can most easily make an opening. 

When a larva leaves its burrow in tho hop vine, it does one of two 
things: either it oats its way into a bed root, or it feeds on the outside 
of tho vine Ix'twoon the bod root and tho surface of tho ground. In very 
rare cases larvao have boon foimd focnling on runners, or rootstocks, 
which were not removed by grubbing in the spring. 

The late {outside) work on the vines 

After leaving tho head of the hop or the inside of the vino, tho larva 
usually attacks tho outsido of the vine and feeds on the sap that flows 
from tho woimd. In some ca.ses tho vino is eaten completely thru, but 
oft^'iior it is held togi-ther by a small shred and enough nourishment 
pas.ses thru to keep the foliage from wilting. After feeding in one place 
tho larva often goes to another, above or below tho old wound, and 
repeats its work. Vines thus attacked often send out extra rootlets above 
the wounded area, and much additional nourishment is received in this 
way. Tho sap is able to asc(>nd in vines of this kind, but the return 
flow of manufactured food material to the roots is cut off. The vine 
swells above the injmed area, duo, no doubt, to the deposition of the 
material being carried downward. The roots, deprived of this food 
supplv, bo(;om(! weaker and succumb more readily to the winter frosts. 
(Fig. 13.) 

The irork in the roots 

Some of the larvae eat their way into the bed loot on hatching, but 
it ia conunoner to find i)artly grown larvae in this ix)sition. Larvae 



Insects Injurious to the Hop in New York 155 

are especially abundant in the roots in unhilled yards, where the roots 
are close to the surface of the ground. Some gnihs make shallow grooves 
on the outer surface, but many work in the core of the root in all directions. 
The writer has found twelve larvae in a single root. As the bed root is 
the part of a plant that lives over the winter and furnishes the growth 
for the coming season, any injury to it is a serious matter. One result of 




Fig. 13. vines broken off from the bed root as a result of the 
feeding of the hop-vine borer. slightly reduced 

The enlargement above the place of attack is to be noted 



this work of larvae is that an opening is made for soil water to seep in 
and freeze; also, fungi may enter and start decay. In yards that have 
been badly infested with grubs, as feeders on either vines or roots, the 
number of dead hills is always much greater the following spring. 

Many grubs are working as external feeders or in the bed root by the 
end of the first week in June, and by the end of the second week nearly 
all have finished their work inside the vines. They mature and complete 
their work in the roots from the middle of July to the middle of August. 



IfHi I. M. livwiJ V 

THK WORK OF THE YOUNG LARVA IX GRASS 

VavW ill the spring of 191"), larvao of Gortyna immanis were found 
workinR in gniss plants in the hopyard.s (fig. 14). The work in grass 
i.«< vory siniihir to tho early work in the hop vine. The grub enters, as 
a rule, elose to the ground and boras upward thru the stem. Injured 
gnis.s may soon be distinguished by the wilting of the central blade. 
The grub continues its work until about the third stage, and leaves the 
grass about the time the larvae arc leaving the inside of the hop vines. 




I"Ui. 1 1. I.ARVA or IIOI'-VINE noRKR IN A ORASS STEM. X 3 

Karly in the spring gra.ss is (•oininoii in many hopyards, giving the 
grubs a good place in whielj to start tJKMr growth ffig. 15). Many larvae 
are found in the gras.s .along the l)orders of yards as well as in the yards 
themselves. It is probable that the moths go to the grass at the sides 
of the yards for shelter during the day, and lay their eggs there at night. 
After the eggs hatch, the larvae fec^d on the gntss and later move to the 
hops. From this it is clear why the edg(>s of th<' yards are often more 
seriously in^urecl than the central parts. No huvac^ were found in grass 
at a distance from the yards. 

In order to see whether other |)lants could act as hosts, weeds of all 
kinds were carefully examined, but in no case were larvae found working 
on them. 



Insects Injurious to the Hop in New York 



157 



types of yards attacked 

Poorly-cared-for hopyards having a growth of grass show more injury 
from Gortyna immanis than do those that arc well cultivated (figs. 16 
and 17). This may be due partly to the less vigorous growth in the 
former type of yard, but it may be attributed in large measure to the 
fact that the eggs of the insect are laid on grass and this grass furnishes 




Fig. 15. grass around a hop hill in may 

Many larvae of Gortyna immanis work in grass at this time 

food for many of the young larvae before they attack the hop. Yards 
newly set out, if near an infested yard, are often seriously damaged. 
] One grower was compelled to reset a new yard four and five times in 
some places before he could get it successfully started. 

Old yards in which the grubs have been allowed to work and multiply 
for a number of years, show the cumulative effect of such work. This 
is one reason given for taking up old yards and setting out new ones 
every five to ten years. 



15vS 



1. M. Hawley 




FjG. 1G. a poorly Klil'T HOPYARD, IN WHICH HAVE BEEN FOUND MANY LARVAE OF 

THE HOP-VINE BORER 




HAVE bEEN FOl'ND AJ WORK 



Insects Injurious to the Hop in New York 



159 




description of the species 

The egg 

The egg of Gortyna immanis (fig. 18) is 0.65 millimeter in diameter 
and 0.43 millimeter thick, flattened above and below. The color of the 
egg when first laid is white or yellow-white, and 
turns to brownish pink in from one to three 
days. The egg is faintly marked on the side 
with about one hundred branching, radiating 
ridges. The micropyle end has a group of 
raised polygonal areas, with a rosette formation 
in the center. 

The larva 

The six stages thru which the larva passes 
may be described as follows: 

First stage. — Length (collected specimen) 3 mm. ; head 
0.3 mm. ; ground color dirty white, with prominent markings 
of old-rose red; sparse -vestiture of setae. Head dark brown 
or black; antennae, ocelli, and mouth parts light yellow 
brow^l. Prothorax, anterior half dirty white, dorsal shield 
dark brown or black. Mesothorax with four rose-colored 
patches on lateral aspect of segments, forming a }>road, 
broken, transverse band. Metathorax with markings similar 
to, but heavier and more irregular than, those of mesothorax. 
Thoracic legs with coxa white, femur, tibia, and tarsus brown. 
Abdomen with segments 1 to S banded similarly to meso- 
thorax, but bands broader, covering nearly the entire segments; tubercles inconspicuous; spir- 
acles small, dark-bordered, surrounded by a light ring; segment 9 more faintly marked; five 
pairs of prolegs; venter lighter but with rose tint on abdomen. In grass, hop heads, and vines. 

(Only the prominent differences are noted in the descriptions following.) 

Second stage. — Tvcngth 3.4-6.4 mm.; head 0.65 mm. (average of seven specimens); ground 
color more prominent, rose-colored markings often less extended and tending to orientation 

in longitudinal axis, on all segments of 
thorax and abdomen; setae about one- 
third as long as diameter of body, and 
tubercles bearing them more prominent. 
Head pale yellow-white, clypeus and la- 
brum darker than other parts; ocelli in a 
dark patch; dark spot on dorsal shield 
divided by a median light line; spiracles 
larger, and especially prominent on pro- 
thorax. In grass, hop heads, and vines. 
Third stage. — Length 6.8-8.4 mm.; head 1 mm. (average of eight specimens); ground 
color more extended and rose patches more regularly arranged; four longitudinal dark lines 
))roken by light spaces; the second (subdorsal) line much narrower than the first and the 
third; tubercles bearing setae dark brown. In grass and vines. 




Fig. 18. EGG OF HOP-VINE 
BORER. X 48 




Fig. 19. 



LARVA OF HOP-VINE BORER, FOURTH 
STAGE. X 5 



160 



I. M. Hawley 



Fourth Ktagf (fiR. 19).— IxjiiRth i) 15 nun.; heiul 1.43 mm. (averaRe of eight specimens);" 
nxjuiid wlor still in<m' extended; .setae and tulx-rcles larRe. In vines and iti Rround 
^ /• ifth Klagc. — LenRih 

17-2.5 mm.; head 2.22 
mm. (averane of ei^ht 
sf)ecimen8); rose mark - 
inps faint in most speci- 
mens, in some entirely 
wanting. In ground or 
in roots. 

Sixth stage (fig. 20).— 

Length 27-48 mm.; 

head 3.'.n mm. (average of eight specimens); rose markings entirely lost; color dirty white; 

fat and unwieldy out of its burrow; tubercles bearing .setae standing out prominently, as do 

brown marks on thoracic and anal shields. In ground. 




Fig. 20. l.xrva of hop-vine borer, full-grown. X U 



The pupa 
The pupa (fiR. 21) Is from 20 to 28 millimeters in length and from 
7 to 9 millimeters in diameter. It i.s usually dark brown, but in rare cases 
Ls lifj;hter in tint. The cremaster consists of two short spines. 



The adult 
The adult (fig. 22) is described as follows by Dr. W. T. M. Forbes: 

The moth is light brown, 
with greeni.sh or pinkish re- 
flections in ct-rtaiii liitlits 
The head anil thorax are of 
the same color. The ordi- 
nary lines on the fore wing 
are slightly paler, nearly 
even, and defined on each 
sifle with a darker gray 
edging; the basal line is 
present; the t. a. line pro 
jects slightly at two ixjiiits 
(on veins Sc and Cu); the 
inner boundary of the t. p., 
or the outer of the two 
principal lines, is sharply 
defined, but the outer is ob- 
scure; the line is U^it at a 
right angli- just Ix'low the 
costa, from which it starts 
at a small siK)t, is slightly 
bent out near the middle (at 
vein Mt), and is incurved 
l)elow; the medial shade is 
single, dark, angle<i at the 
low«-r side of tlio cell, imd w 
infgulnr, esjM'cially .hIhiv*-, .-mrl 




Fig. 21. im pae of hop-vine horer, showing variation 

IN Sl/E. X IJ 

a\(<<l Ix'low; the st. line (shortly before the margin) is 
double toward the inner margin; there is a dark terminal 



Insects Injurious to the Hop in New York 



161 



line; the orbicular spot is erect, the reniform normal. The hind wing is grayer, with a 
somewhat pinkish fringe, dark veins, and an obscure pale and dark t. p. line, female 
larger than male. Spread 40 to 51 mm. 








e^^"^ 



i^y s Tf 



»•* •»' III I .,B> ^r \ 



Fig. 22. adult female of hop-vine borer. X 2 



LIFE history and HABITS 

The egg 

The eggs of Gortyna immanis were said by Dodge (1882) and later writers 
to be laid on the tip of the hop vine by overwintering females, but the 
writer has never seen an egg in this position and has no evidence that 
they are ever so placed. Under field conditions eggs have been found 
only on grass, and here they have been found in large numbers. 

Prior to 1915 eggs had been found deposited in various places in 
laboratory and field cages, but no eggs that were known to be those of 
G. immanis had been found under field conditions. In the spring of 
1915 a search was made for eggs and young larvae, and on May 10 larvae 
were found working in grass stems and eggs were found on dead grass 
blades from the same root. In August' of that year cages were built 
over hop hills on which grass was growing, and full-grown grubs and 
pupae were placed in them. On the grass in one cage eggs were found 
on September 1. They were laid both singly and in small groups. Most 
of the eggs were attached to the outer surface of the grass. On 
September 6 many eggs were found in the axils of the grass stems, in 
all cages. Several lots of eggs were found in the field near Sangerfield 



162 



I. M. Hawley 



on St'ptoinlMM- 7. and from that time on (here wjis little trouble in locating 
eggs on gras-^ in any yard that had Iuh-ii infested by grubs. During 1915 

eggs were found nowhere except on gra.ss 
plants. (Figs 23 and 24.) 

The egg stage lasts about eight months. 
Eggs are laid from the middle of August 
to the last of September, and hatch from 




Fig. 23. eggs of hop-vine borer 
on a grass stem. x 3 

the last week in April to the last of May. 
A distended female opened in 1014 con- 
tained SCiO eggs. ( )thers examined in 1015 
hatl 725, 457, and (512 eggs, respectively. 
No data were gathered on eggs deposited. 
It is apparent that the nmnber of eggs Fig. 24. • eggs of hop-vine borer 
laid by a sk,gh- ,„„lh nu,v l,o large. Not ^.^^^^^^rVT °"" 
all eggs hatch, a.s many turn black and 

shrivel .soon aft«'r being laid. Both shrivc'led and healthy eggs are found 
in the same egg mass, and as many as fifty per cent may diy up — due. 
no doubt, to lack of fertilization. 








I 



Insects Injurious to the Hop in New York 



163 



Eggs are laid soon after the moths emerge. The data for three indi- 
viduals arc given in table 1: 



TABLE 1. 


Length of Time between Emergence 
1915 


and 


Oviposition of Three Moths, 




Date of emergence 






First 
eggs laid 


Days 
intervening 


August 25 


September 2 
September 5 
September G 


8 


August 31 


5 


August 26 


11 







The larva 

In order to find the number of stages thru which the larva passes in 
its development, a series of head measurements were taken. Since the larva 
breeds in vines and beneath the surface of the ground, it is impossible 
to find the cast skins, and so grubs were preserved in alcohol during the 
^mmmer of 1914. These were later examined and the transverse measure 
of the head was taken, as given in table 2: 

TABLE 2. Head Measurements of Larvae Collected in 1914 



Stage 


Number of 
specimens 


Diameter (in millimeters) 


Greatest 


Least 


Average 


1st 

2d 

3d 


1 
7 
8 
8 
8 
8 


0.30 
0.68 
1.06 
1.50 
2.46 
4.06 


0.30 
0.60 
0.92 
1.37 
2.06 
3.80 


0.30 
0.65 
1.00 


4th 

5th 

6th 


1.43 
2.22 
3.91 







It is seen from the above data that the larva of G. immanis probably 
passes thru six stages with five molts. The entire length of the larval 
period is from nine to twelve weeks, since the young larvae hatch from the 
last of April to the middle of May and pupation occurs during July and 
the first half of August. No larvae have been successfully bred thru. 

Smith (1884) reports that the larva makes a rude cell in which to 
pupate. Comstock (1883) did not observe this to be true. In rare cases 



ir>4 



I, M. Hawley 



the writer hiis found a pupal cell. Whether or not one is formed de- 
I^'nds on the texture and the moisture eontent of the soil at the time of 
pupation. If the soil is of tlie eonsisteney of elay and is easily packed, 
a (ill may be formed. ■ 

The pupa 

There is a wide variation in the size of pupae (fig. 21, page 100). as 
also in the A-£V of adult moths. The writer believed that the small pupae 
must Ik^ those of males and that the large ones would develop into females. 
Breeding shows that this is not always true, since in some cases females 
have iM'cn reared from pupae of the smaller size. 

In 11)14 full-grown larvae of (7. immanis were taken into an unheated 
field laboratory. The length of the pupal stage under these conditions 
wa.s found to Ix' as given in table '.i: 

T.\BLK 3. Length ok Plpal Staok kor Four Specimens under Laboratort 

Conditions 



Date of pupation 



Date of 
emergence 



Days 
intervening 



July 2 

July 3 

July 5 

July 6 

Average, 30 days. 



August 8 
August 7 
August 9 
August 11 



37 
35 
35 
36 



From the above data it is .seen that tiie pupal stage lasts a little over 
one month in the laboratory. Observations by the writer indicate that 
in the field it varies from four to six weeks. Pupation occurs in the 
field during July and in the first part of August, and moths emerge during 
August and Sei)t<'mber. In l!tl4 the first pupa wa.s found on July 2. 
and in llHo on July V». In 1U14 the fir.st moth emerged on August 10, 
and in 1915 on August 11. At Waterville the writer found newly trans- 
formed moths in field cages ;us late its the middle of September. 

In most caHes the full-grown larv;i leaves the root or the vine and 
comes close to the surface of the ground before pupation. The pupa 
is often found .some di.stance down the side of the hill — a foot from 
the place of larval feeding o|K'rations. In rare cases the pupa may be 



Insects Injurious to the Hop in New York 



165 



found near the root and even beneath it. The moths on emerging often 
leave the pupal skin projecting above the ground. Smith (1884) reported 
that G. im?nams usually winters in 
the pupal stage, but after three 
years of observation the writer is 
convinced that all pupae change to 
adults in the fall. Cages were ex- 
amined late in Septembei-, and all 
healthy pupae had transformed. 

The adult 

Adults of G. immanis, being col- 
ored much like dirt, dead leaves, 
and hop poles (fig. 25), are seldom 
seen in the field. It is not uncom- 
mon to search for moths in a cage 
for some time and then find them 
resting quietly a few inches away. 
If disturbed they usually flutter 
their wings and crawl a short dis- 
tance, but do not fly far if at all. 

After depositing eggs the moths 
die in a very short time, in most 
cases in about a week. In one case 
a moth lived for twelve days after 
completing oviposition. Sweetened 
solutions were placed in some cages, 
but did not greatly prolong life. These data were obtained by isolating 
moths the abdomens of which indicated that they had been laying eggs. 

seasonal history 

The eggs of Gortyna immanis are laid in the fall on grass in and around 
hopyards. The eggs hatch the following spring, in April or May, and 
the young larvae make their way into grass or hop plants. In grass 
they eat into the stem near the surface of the ground and feed upward, 
killing the central blade. They leave the grass at about the time other 
larvae leave the inside of the hop. 




Fig. 25. adult hop-vine borer on hop 
pole. slightly reduced 



166 1- ^^- Hawlkv 

In the hop the younp: Kruhs enter the part that is the most readily 
avjiilahle and ejisy to penetrate. This may be the hcail or any part of 
the vine. If the hirva enters the head, it drops to the ground in about 
two wtH'ks and helps to increase the lar^e mnnber already working in 
the vine near the root, .\bout the first of June, when the larva is in the 
thiril or the fourth stage, it stops inside work and either feeds on the 
outside of the vine, nearly or (|uite .severing it, or makes burrows in the 
root. In July or the fii-st part of August the larva pupates, and the moth 
emerges the last of August or early in September. The moth deposits 
eggs, whieh rest over the winter on grass. The moth dies soon after 
oviposit ion. 

RELATION OF CLIMATIC AND SOIL CONDITIONS TO SEASONAL HISTORY 

Weather conditions have some influence on the life history of Gortynn 
immanis. \ late, cold spring retards the development of the larvae 
somewhat, while warm weather hastens its growth. The winter of 1913-14 
wa-s attendcHJ with heavy snows which covered the ground in the hop 
country until late spring, while that of 1914-15 was open and the groiuul 
was not covered. A laiger number of grubs were present the following 
spring imder the former conditions, in a yanl that was under clo.se obser- 
vation. The snow cover may act as a blanket for the overwintering eggs. 

The larva works in any kind of .soil. Yards on sandy soil, however, 
are less afTectcd than those on gravel, clay, or loam. 

NATURAL ENEMIES 

Predatory enemies 

The skunk. — An im|)ortant destroyer of the larvae, and probably of 
the pupae, of (inrtymi intnianis, i.s the skunk. About July 1, when the 
grubs have reached maturity, numerous holes may be seen in hop hills 
where, skunks have been <ligging for the fat, juicy larvae. vSonietimcs 
the .skunk digs the dirt entirely away from the bed root, leaving only 
alKuit half of the hill .standing (fig. 2t)); at other times it pushes the 
dirt jiside with its no.se, making a small, deep hole about three inches 
in diameter. Not every hill is attacked, and growers .say that the animal, 
hearing the grub feeding, digs in only where it is sure its efforts will be 
rewarded. The skunk dix's not always find all the grubs that are present ; 



Insects Injurious to the Hop in New York 



167 



the writer has often taken both larvae and pupae from hills in which 
skunks had recently been working. It is seldom that the vines arc injured 
by the work of the skunk, unless they have been badly eaten by the grub 
and are hanging by a mere shred. 

As a control measure the skunk does much good by reducing the number 
of larvae and pupae that would complete their development. It does 
not, however, reduce the injury of the year, for by the time the skunk 
becomes active the larvae 
are full-grown and the 
damage is done. 

Predacious beetles. — Sev- 
eral species of carabids 
feed on the larvae of 
G. immanis, the most dar- 
ing of these being Cal- 
osoma calidum Fab. Both 
the larva and the adult 
of this species (figs. 27 
and 28) are active in at- 
tacking the grubs of G. 
immanis. The adults, at 
least, of other smaller cara- 
bids feed on the larvae of 
G. immanis in the younger 
stages. The following 
species are known to be 
predacious : H arpalus 
pennsylvanicus Dej.; Pterostichus lucublandus Say; Pterostichns stygicus 
Say; Amara impuncticollisSay. 

In breeding cages the writer has found dead pupae and adults with holes 
eaten in the sides of the abdomen. Carabids found in the cages are 
beheved to have done this work. A small carabid collected in the field 
and placed in a bottle containing several pupae had destroyed one before 
the laboratory was reached. Masses of eggs partially eaten by a preda- 
tory enemy have also been found, and carabids were present in the cage 
at that time. 




Fig. 26. a hop hill showing the hole made by a 
skunk in digging for the larvae of the hop- 
vine borer 



ill 



168 



I. M. Hawley 



Parasites 

Hymenopterous parasites. — The braconid Microplitis gortynae Riley'' 
is a common parasite on the larva of Gortyna immanis. In 1914 the writer 

found large numbers of braconid cocoons 
close to depleted larval skins of the grubs. 

^ Eighty cocoons were found with a single 

skin. These were kept over winter but 
adults did not emerge. On June 11, 1915, 
the writer found more of the cocoons when 
digging grubs. Some adults had emerged I 
and more were just coming out at the 
time. The braconids were found on top 
of the ground and crawling all thru the 
dirt. Some specimens taken to the lab- 
oratory and placed with partly grown 
larvae began laying eggs at once. One 
whipped its 



Fig. 27. larva of predacious 

beetle. about natural size 

Calosoma calidum 

larva, when attacked, 
body back and forth, crawled between 
pieces of dirt, and even turned com- 
pletely over. In spite of these efforts 
the parasite still clung firmly until its 
object was accomplished. 

For two weeks after the observa- 
tion just recorded, braconids were 
often seen crawling in search of a 
host in the infested hopyards about 
Waterville; and later in the summer 
the cocoons were again found, both in 
cages and in the field. The larva of 
the parasite apparently leaves the 
grub just as the latter is about to 
pupate. A cocoon of a braconid para- 
site was found with a dead grub on 
July 9; a specimen belonging to the 
genus Aenoplex^ emerged from this on August 15. Chalcid parasites 
iSynaldis s p.) were bred on August 10 from grubs found on July 9. 

3 Determined by A. B. Gahan thru the kindness of Dr. L. O. Howard. 




Fig. 28. 



ADULT OF PREDACIOUS BEETLE. 
SLIGHTLY ENLARGED 

Calosoma calidum 



Insects Injurious to the Hop in New York 169 

Dipterous parasites. — In the summer of 1914 a tachinid fly, Frontina 
frenchii Will.,^ was reared from a full-grown larva. On June 12, 1915, 
in examining work in vines, a grub skin of Gortijna immanis was found 
with many dipterous larvae crawhng in it. Dr. O. A. Johannsen has iden- 
tified adults bred from these larvae as Masicera myoidea Desvoidy, 
also a tachinid. 

Fungous parasites. — In both 1913 and 1914 dead grubs were found 
which were covered with a fungous growth. In the spring of 1914, F. M. 
Blodgett succeeded in obtaining from one of these a culture of what 
appeared to be Sporotrichum globuUferum. Later spore suspensions of 
this fungus were injected into hop hills, but no indication of its inoculating 
the grubs could be found. 

CONTROL 

The control of Gortijna immanis as practiced in the hopyards of New 
York State has been almost entirely based on cultural measures. Pinching 
the tips of the hops that were muffle-headed has been recommended 
(Dodge, 1882, and later writers), but since few larvae enter the heads 
this alone is insufficient. Another control method suggested (Dodge, 
1882, and others) is to dig the dirt away from the vines and the roots 
in spring, and leave them in this condition until late in July or early in 
August, at which time, it is advised, a composite consisting of equal 
parts of salt, quicklime, and hen manure should be added. It was beheved 
that under these conditions the vines would become so tough that the 
grubs could not injure them. So far as the writer knows, this method 
is not practiced at the present time. 

In order to test the effect of leaving the roots uncovered, as suggested 
above, the dirt was removed from ten hills in two yards about June 1. 
When one yard was examined later, the vines in these ten hills were found 
to be less developed than the vines in adjacent hills. There were no grubs 
in this yard. In the other yard grubs were found working in both the 
vines and the bed roots. 

Still another method of control that has been recommended (Dodge, 
1882, and other writers) is high hilhng. In hilling, men throw dirt around 
the vines with shovels, covering the hill several inches deep, or plow 

« Determined by J. D. Tothill. 



170 ' ^' Hawlky 

close to the hill turning a funow ovor it. This is done in June or carl\ 
July. Some growers claim that hilling draws the grub to the surfa< 
and away from its place of feeding on the vine. The writer has not founl 
this to 1m' true. In several yards hilleil very high, grubs have been found 
in quantities in and around the bed root — a foot or more below th 
surface of the groiuid. 

In highly hillml, well-fertilized yanls, the vines often send out rootlet > 
alK)ve the injured areas. These supply nouri-shraent to so large an extei 
that vin(»s nearly .severed are often kept alive by this means. Hilling i- 
a good practice for this reason if for no other. 

A hop root sends up many more vines than are needed for cultural 
purix)ses. When the hops are tied the second time, which is usual! 
about June 1, these extra vines are pulled up or cut off with a knife. Th 
practice is of use in grul> control if done in the right manner. At thi- 
time many of the grubs are working on the inside of the vines, and if tl 
vines are destroyed the grul)s will be killed. It is better to pull the vini 
out than to cut them off, for. if larvae are working in the vines near tl 
crown, the cut may come above them anil they are then free to cra^\l 
out and enter vines that have been twined on the poles. The writer h: 
seen many grubs in the stumps of the vines just below the place whei 
they were cut off, and has observed them crawling to adjacent plant-. 
If the vines are pulled, they break off where they join the root. All 
sprouted vines should l>e tak"n from the yards. As grubs work in the late 
shoots just coming above the ground, these also should be removed n 
this time. In lOlo most of the grubs were outside the vines by June ' 
and the practice of sprouting, to be effective, should in ordinary yeai 
Ik' completed before June 1. 

An old recommendation (Smith, 1884) is to place wood a^^hes aroun 1 
vines or scatter them on top of the hills. In 1914 one grower did thi- 
alwut June l.'i. On examining that yard some time later, the writ( 
found live grubs to Im' numerous in every hill and dead vines were unu- 
sually plentiful. 

Sometimes growers resort to digging out tli(> larvae. This ha.>< Ihhmi 
doiH' in early June, when the work outside the vines was just beginiiini: 
The .soil is removed from around the hills down to the bed root with a hot 
and the dirt is worked away from between the vines with a pointed stick 



Insects Injurious to the Hop in New York 171 

in order to remove any grubs that may be feeding deep down near the 
roots. William Durar, working for George Allen, a grower, at Sanger- 
I field, New York, found that it took twenty-eight hours to go over 267 
hills. He averaged, therefore, between 9 and 10 hills an hour, but in 
addition to digging out the grubs he removed the dead vines and trimmed 
off the lower arms. If all the time had been spent in digging grubs, it 
is probable that 12 hills an hour could have been gone over, or 120 hills 
in a day. At this rate it would take about six days for one man to dig 
one acre, amounting, at S2 a day, to $12 an acre. Another grower reports 
that grubs can be dug at the rate of 200 hills a day — a cost of $7.50 
an acre. This makes digging a rather expensive process. 
, In digging grubs, vines that are weakened by feeding may be broken 
j off, and in ordinary practice of this kind the larvae working in the roots 
, would not be found. Men in the hop sections are needed for other work 
at this season of the year, and it is difficult to get help that can be relied 
; on to do this work in a proper manner. For these reasons, the writer 
' undertook a series of experiments to see whether an effective method of 
I control could not be found at a more reasonable cost to the grower and 
I with less demand on greatly needed labor. The results of these experi- 
ments are given in the following pages. 



Experiments in 1914 

Most of the experiments in 1914 were conducted in the Gallagher 
yard at Sangerfield, New York. The soil in this yard is a gravelly loam. 
At the time when most of the materials were applied, the soil was mellow 
and slightl}'- moist and phosphate had been added at the rate of a few 
handfuls to each hill. Experiments were conducted in several parts of 
the yard at once, and counts were made from several hills in each of these 
plots. 

The test of efficiency for most materials is that few live grubs are to 
be found in the hills when counted. The number of grubs to the hill 
varies greatly, and so a count of a small number of hills may not give a 
' true average; it may be said, however, that in any case when three or 
more grubs are left alive, the material may be considered ineffective, as 
three grubs can destroy an entire hill. 

The results of the experiments conducted in 1914 are given in table 4: 



172 



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Insects Injurious to the Hop in New York 



173 



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174 \. y\. Hawlky 

Experiments with carbon disulfid 

CixrUm disulfid wivs tried jis a control mca.'^uro against tho larvae in 
the ('.alla^her yard. In the first exixM-inient, on July 2, a hole wan made 
in the soil with a sharpened stick and the liquid was poured into it from 
a l)ottle. The hole wius then filled in. A pint of material was used in 
eipht hills. One hill wius opened in fifteen minutes and the remainder 

T.VHLE o. Rksults of Experiments with Carbon Disulfid in 1914 — Series I 
(Time between injection and examination, from 48 to oO hours. No injury to vines) 


Experiment 


Distance 
of appli- 
cation 
from 
rocjt 
(inches) 


Number 

of 
injections 


Quantity 

used 
in each 
injection 
(cubic 
centi- 
meters) 


Depth of 
injection 
(inches) 


Number 

of grubs 

found 


Depth of 
grubs 
when 
found 

(inches) 


Con- 
dition 
of grubs 


21 


3 


1 


4 


6 


2 


3 


Sick 






22 


3 


1 


8 


6 


1 


3 


Dead 






23 


:i 


•J 


2 


6 


2 


2 


Ahve, 
sick 


24 


3 


2 


4 


6 


1 


5 


Dead 






25 


6 


1 


2 


6 


1 


3 


Dead 






26 . ..• 


6 


1 


4 


G 


2 


4 


Dead 






27 


6 


1 


8 


6 


1 


4 


Dead 






28 


6 


2 


2 


6 


1 


6 


Dead 






29 


6 


2 


4 


6 


1 


5 


Dead 






30 


6 


2 


8 


6 


2 


4 


Dead 


32 


12 


1 


4 


6 


1 


3 


Alive, 




active 


:i3 


12 


1 


8 


6 


2 


( 5 

■ 7 


Dead ■ 

Nearljl 

dearT 


34 


12 


2 


2 


6 


1 


4 


Sick 






36 


12 


2 


4 


6 


1 


3 


Alive 







Insects Injurious to the Hop in New York 



175 



TABLE 6. Results of Experiments with Carbon Disulfid in 1914 — Series II 
(Time between injection and examination, from 48 to 54 hours. No injury to vines) 



Experiment 


Distance 
of appli- 
cation 
from 
root 
(inches) 


Number 

of 
injections 


Quantity 

used 
in each 
injection 
(cubic 
centi- 
meters) 


Depth of 
injection 
(inches) 


Number 

of grubs 

found 


Depth of 
grubs 
when 
found 

(inches) 


Ck)n- 

dition 

of grubs 


20 


3 


1 


2 


6 




3 


Dead 


21 


3 


1 


4 


6 




4 


Dead 


22 


3 


1 


8 


6 




3 


Dead 






23 


3 


,2 


2 


6 




5 


Dead 


24 


3 


2 


4 


6 




4 


Dead 


25 

1 

2 

3 


6 
6 
6 


1 

1 
1 


2 
2 

2 


6 
6 
6 




4 
3 
2 


Dead 
Dead 
Dead 


26 

1 

2 

3 


6 

6 
6 


1 

1 
1 


4 

4 
4 


6 

6 
6 




2 

4 
6 


Alive, 
sick 
Dead 
Dead 


27 

1 

2 

3 


G 
6 
6 


1 

1 
1 


8 
8 
8 


6 
6 
6 




3 
2 
5 


Dead 
Dead 
Dead 


28 

1 

2 


6 
6 


2 
2 


2 
2 


6 
6 




2 

7 


Sick 
Dead 


29 

1 

2 


6 
6 


2 
2 


4 
4 


6 
6 




3 
5 


Sick 
Dead 


30 


6 


2 


8 


6 


1 


4 


Dead 



in from one and one-half to two hours. Two grubs in the first hill opened 
recovered from the effects of the vapor, but 57 in the other seven hills 
were all dead. Many vines were injured. On the following day one pint 
of the material was applied to twenty hills. From four to seven hours 



170 



I. M. Hawley 



after the treatment, 1 IS jrnil)s were found; of these, 106 were dead, 
6 were dying, and 6 were alive. The live grubs were on the opposite side 
of the iKile from the injection, or on ruimers at some distance from th€ 
root. The vines in some of the hills wore killed. 

Conditions at this time were favorable for the effective working of tht 
vapor. The soil was slightly moist and was mellow, and the yard wai 
hilled high. In addition to the grubs, millipedes and l)ettle larvae wen 
killed. By this time th(^ larvae were full-grown and were becomin| 
scarce. \ few were found, however, and these were placed in the centei 
of the hills and doses of different strengths were tried against them. Th« 
results are shown in tables 5 and (pages 174 and 175). From thes« 
tables it is seen that, under ideal conditions, doses as low as two cubic' 
centimeters to a hill were foutid effective. Of all the materials tried in 
1914, carbon disulfid alone showed signs of success, and therefore the 
writer decided to test the material more fully in 1915. 

In order to test the effect of carbon disulfid on the hops, another series of ex- 
periments was conducted. The moi(^ important results are given in table 7| 

TABLE 7. Results of Injury Experiments with Caabon Disulfid in 1914 









Quantity 








Distance of 




used in each 


Depth of 


Resulting 


Experiment 


application 


injections 


injection 


injection 


injury to 




from root 


(cubic cen- 


(inches) 


plant 








timeters) 






1 


Next to root 




8 


6 


2 dead \'ine8 


2 


Next to root 




4 


6 


None 


3 


f) inches 




16 


6 


None 


4 


<i inches 




16 


6 


None 


5 


(i inclies 




16 


6 


None 


6 


t) inches 




16 


6 


None 


7 


() inches 




16 


6 


None 


8 


6 inches 




16 


6 


None 



Experiments iji 1915 
Experiments irith cnrhon rh'sulfifl 

In the spring of 1915, the writer again .started experiments with carlx)n 
disulfid. These included investigation not only of its use in grub control, 
but also of the resulting injury to hop plants. The results are given in 
table 8: 



Insects Injurious to the Hop in New York 



177 






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178 



1. M. Hawlky 



In fonductinp; the cxj-K^rimpnts recorded al)Ove, the writer had to con- 
tend with :i serious liaiuheap in the way of frequent and heavy rains. 
Much of the soil in the hop region has some clay in its composition. When 
moist, a soil of this nature is so compact that the vapor meets an impass- 
al)le harrier. With injections as far as six inches from the vines, it was 

found that the carbon disulfid was 
ineffective. Increasing the do.sc did 
not give better results. As a l£ist 
resort injections near the plants, in 
njost cases directly above the roots, 
were tried. The result in this case 
was still ineffective in controlling 
the grubs and in many cases was 
disastrous to the plants. In the 
experiments recorded in table 8, 
vines were killed as follows: Hicks, 
H 2, one vine; B 4, four vines; D 2, 
three vines; Hovey, B 3, many 
vines; Thayer, fifteen vines; Camp- 
bell, nine vines; Moakler, six vines; 
W'alradt, many vines. The depth 
of injections was from two to three 
inches. 

\\ itli the object of finding a way 
to place the liquid rapidly and uni- 
formly in the soil, the writer, with 
the aid of F. M. Blodgett, devised 
an injector (fig. 29). So far as the 
w liter knows, nothing of the kind 
is at present on the market in this 
count ly. 

From the data in table 8, it is 
seen that the coinils of living and of dead grul)s show only 27.8 per cent 
control for the sea.son's work. Sick grubs in the counts are considered 
JUS live ones iM'cau.se, due t(» the length of time and the weakening of the 
vaiK)r density b<>tween injection and counting, sick ones would no doubt 
luive recovered. The average lunnber of live grubs per hill is given to 
show the comparative averages for check and for treated i)lots. 




Fl(.. ■_".). TWOTVl'liS OF INJKCTORb lOR I SE 
IN TREATING SOIL WITH CARUON PISCI-FIl) 



Insects Injurious to the Hop in New York 



179 



Taken as a whole, the results are very unsatisfactory. The writer 
believes, however, that in some soil and under ideal moisture conditions 
good results may be obtained. Since these conditions cannot be con- 
trolled the use of carbon disulfid is of doubtful importance. 

Injury to hop vines from carbon disulfid. — Carbon disulfid will kill a 
hop vine or root whenever it comes into actual contact with it. The 
writer has noticed that vines which are badly eaten by the grubs are killed 
oftener than those that are not. A series of experiments in moist sandy 
soil showed that 15 cubic centimeters of carbon disulfid placed close to 
the vines had no serious effect. The sandy soil, being porous, no doubt 
allowed a better spread of the vapor. The results of an experiment in 
the Gallagher yard, where the soil is a gravelly loam, are given in table 9: 

TABLE 9. Results of Injury Experiments with Carbon Disulfid in 1915 
(Injections were made on June 16; plants were examined on July 10) 



Experiment 


Quantity 

used 
in each 
injection 
(cubic cen- 
timeters) 


Number 

of 
injections 


Distance of 

application 

from root 

(inches) 


Number 
of live 
vines 


Number 

of dead 

vines 


la 

lb 


16 
8 
24 
12 
32 
16 
21 
24 


1 
2 
1 
2 
1 
2 
2 
2 


4 
4 
4 
4 
4 
4 
4 
4 


2 
4 
2 
2 




1 


2 



2a 

2b 


2 

2 


3a 

3b 


4 

4 


4b 

5b 


4 
3 



Experiments with poison bait 

In spite of poor results obtained in 1914 from the use of poison bait 
it seemed possible that it might be applied successfully, and on June 11, 
1915, a plot in the Gallagher yard was treated with a bait composed of 
2| pounds of bran, | pound of white arsenic, 1^ pint of molasses, and the 
juice of an orange. This is stronger in arsenic than the mixture used 
against the army worm. 

A rainfall of 0.26 inch occurred soon after this experiment was started, 
and therefore another plot was treated on June 12 with a mixture of the 
same strength. The material was placed close around the vines, the dirt 



ISO I. iM. Hawlky 



1 



iH'ing romovod to make this possible. On Juno 14 the following counts 
\v(Mv made: in the plot treated on June 11 there were 30 grubs in ten 
hills, of whic-h 28 were alive and 2 were dead; in the plot treated on June 
12 there were 27 grubs in ten hills, all of whieh were alive; the check 
showed 29 grubs in ten hills. CJrubs placed in a jelly glass with poison 
bait on June 12 were sick on June 13 and died on June 14. It is prob- 
able, therefore, that these larvae will feed on poison bait when the pre- 
ferred hop vines are not present, but that they will not touch it under 
field conditions. A bait applied in May to catch the hatching larvae 
might jirove elTective. 



unt 1 



Experiments with para-dichlorobenzene 

ParaHlichlorobenzene has V)een successfully used against various pei 
of stored grains. Duckett (191o) descrilxid its use, and from his account 
the following data are taken: Para-dichlorobenzene is a colorless, crystsil- 
line substance with a boiling j^oint of 341. G° F. It volatilizes readily as 
a colorless vapor with an ether-like odor. This vapor, which is five times 
as heavy as air and twice as heavy as carbon disulfid vapor, is harmless 
to human b(Mngs but is a sjx^cific poison for insects under many condi- 
tions, killing by action on the nervous system. The insect l)egins quiver- 
ing and finally turns on its l)ack and, still (luivciing, dies. The cost is 
15 cents a pound in l)arrel l<jts, and 35 cents a pound in small ([uantities. 

It may be added that in 1915, due to the war, the price of jiara-dichloro- 
benzene rose to 35 cents a i)ouiid in large lots and 60 cents a pound in 
small fjuantities. and it w:ts soon imjKJSsible to obtain it at these pi'ices. 
However, it is now manufactured in this country and ma}'' be obtained 
at a nmch lower cost. So far as published results indicate, its use is rcc- 
onunended only in the case of certain stored-grain and household insects.. 

The writer tested this material against the larva of Gortymi itnmanis. 
The results of three experiments are given in table 10. 

In all cases the characteristic odor was noticeable and crystals could 
still be found in the hills when they were examined. Of the seven live 
grubs in the Hicks yard, two were near the surface and thnu^ were on 
runners at some distance to one side. Sick grul>s were counted as dead, 
.since the material was still active and would doubtless have killed them 
if left undist»nbed. Dead Lachnosterna larvae and carabids also were 
found, but millipedes were usually able to escape the action of the vapor. 



I 



Insects Injurious to the Hop in New York 



181 



Dead grubs are soft and black, and sick grubs are often slightly dis- 
colored. The vapor would no doubt spread more rapidly in normal years, 
free from the frequent heavy rains, and it will be interesting to see the 
effect of the material on the grubs under ordinary conditions. No plant 
injury was noticed during the experiments, but 56 grams of para-dichloro- 
benzene placed around one hill killed the plant in eleven days. 

TABLE 10. Results of Experiments with Para-Dichlorobenzene 
(Ten hills counted in each yard) 



Yard 


Date 
when ex- 
periment 
was 
started 


Date 
when ex- 
periment 
was 

closed 


Amount 

of 

material 

used 


Larvae found 


Per cent 

of 

control 


Total 
number 


Number 
dead 


Number 
sick 


Number 
alive 




June 18 
June 21 
June 21 


July 10 
July 10 
June 28 


A few crys- 
tals 

A few crys- 
tals 

A few crys- 
tals 


14 
39 
37 


12 

28 
32 


1 
4 
3 


1 
7 
2 


92.8 


Hicks 


82.0 




94.6 







The ideal insecticide for grub control would be a material with long- 
lasting effect, which could be easily placed in the soil when early hilling 
is practiced. Para-dichlorobenzene may act successfully in this way. 
Its insolubility in water and its activity in the soil over such long periods 
of time would tend to indicate this. More study should be given to this 
side of the work. 

Recommendations 

The following practices are recommended for control of the hop- vine 
borer : 

1. Remove all extra vines before June 1. Pull out the extra vines and 
remove them some distance from the yard. 

2. Hill the hops, so as to give the extra rootlets an opportunity to grow. 

3. Practice clean cultivation; in other words, remove the grass from 
the yard. 

4. Keep a plowed border several yards wide around the field. 

5. For an insecticide, experiment with para-dichlorobenzene, using a 
few crystals in each hill and coveiing with about two inches of dirt. This 
should be applied about the third week of May. 



» 



182 



I. M. Ha^xey 




TIIK IU)I' 1{HI)BUC. 
(Paracalocoris hawlcyi Knight) 
During \\\v past few years hoj) |)lants in the yards about Waterville, 
Mow York, csix'cially in those in the vicinity of Sanjiorfield, have shown 

(•(»nsj)icu()iis injury of the fohage 
l)y perforations of the leaves, 
and also a stunting; and defor- 
mation of the stems. In June, 
1913, the vines in several yards 
at 8ang(M-field were notably in- 
jured in this manner. Careful 
examination of the affected 
plants disclosed the presence of 
larp;e numbers of red nymphs 
witii white markings. When 
these yards were examined early 
in .hily the nymphs were feeding 
on the vines and sap was flowing 
from the wounds made by them. 
.\ few adults were taken at that 
time, which later were found to 
Ix'long to the family Miridae. 
Hecause of their striking color 
I he writer has called them the 
hop redbug. Each year since 
1018 the insect has increased 
gicatly in numbers and has 
caused more and more injurJ^ It 
may now be found in yards ten 
miles from Sangerfield, but it does 
not apjx'ar (o have readied the C'ooperstown district thirty miles distant. 
The writer submitteil a large series of specimens for examination to 
II. II. Knight, who reported them as representing a new species which 
he described as Paracnioron'.s hnwlcj/i. Later the determination was 
confirmed l)y W. L. McAtee, who in addition described several varieties 
of the species. 



Fig. ;J0. work of the hop redbug on hop 
vine am) lkaves. reduced 



Insects Injurious to the Hop in New York 



183 



NATURE OF THE INJURY 

The injury caused by the hop redbug may be recognized by the deformed 
and stunted vines and the irregular holes in the leaves (figs. 30 and 31). 
The earhest injury is made evident by many hght spots in the still folded 
leaves, and on close examination it is found that the epidermis is broken 
on the underside. Later, as growth of the leaf continues, a dead area is 




Fig. 31. leaves showing results of feeding of the hop redbug 



produced, and when this drops out an irregular hole results. The early 
work is found about the middle of June, and by the middle of July the 
leaves may be completely riddled. 

In later stages the nymphs may feed on the vines, causing a flow of 
sap from the punctures. As the vine grows it often becomes stunted on 
the side attacked, and by the continuance of its growth on the opposite 
side a sharp bend is formed. A plant is often weakened so that its cling- 
ing power is lost; the main stems tend to hang down, and often all the vines 



184 



I. M. Hawley 



n 



of \\\v lull slip down Jiroiuid the base of the polo (fig. 32). The older 
nymphs may feed also on the hiiis and the hop hcatls, but scM'iotis injury to 

thcst' parts could not be detected by the 
\vi itci-. Pole yards are attacked worse than 
arc string yards, and in string j-ards the 
\incs on the poles show more injiuy than 
do those on the strings. 

The work of the hop rcdbug is similar 
to that described by Theobald (1895) for 
a related species, Calocon's fidvonmculatus 
I)('g.. which has caused some injury to the 
hop in I'^ngland. 



DKSCRIPTIOX OF THE SPECIES 

The egg 
rhe egg of the hop redbug (fig. 33) is 1.6 
Miillimctcrs long, 0.4 millimeter wide, and 
0.2 millimeter thick. The color is dirty 
white. The egg is curved, with two promi- 
nent, pure white, incurving hooks on the 
micropyle end; one hook 
is pointed and the other is 
blunt at the tip. The sur- 
face of the egg is smooth 
and glossy. 




Fig. 32. a hop hii.i. so weakened 
bv the work of the hoi' rkd- 
bl'g. that the vines h.we 
slipped down the pole 



The nymph 
The five nymphal stages may be described as follows: 

First stage (fig. .'VI). — Ixingth 1.3 mm. (average of ten specimens); 
(reneral rolor liph' tomato red; a median variable light line extending 
from near the cephalic end of the head to near the posterior end of the 
Hecond abdominnl wnmeiit, faint in .some sfx'cimeiiH but in others dis- 
tinctly whit*'. Ixjrdered laterally oti the thorax by day-colored patches. 
.VnUmnae »vith the basal segment .slightly dubln-d. t^nnato red, and 
Hparsely cloth'-d «ith hairs; the second s«'gment sparsely hairy, white 
(2 5) and n^d (3 .">); the thinl si'gment spanwly hairy, wliite (!) and 

n-d (''; the fourth s<'Kment densely hairy, clay color with a .small white spot at base. 
Coxa of leg white, trochanter white, femur red, tibia with thn'e red jind thre<' white bands 
of varying breadth, tarsus white with dark tip, claw dark. F^ach abdominal segment bearing 
a row of dark setae; head and thorax with irregularly arranged .setae. Beak white with dark 
tip. Venter clay color. In a few cu.ses the median line wanting, as well as all white bands, 




Fig. 33. egg of 
hop redbug. 
X 24 



Insects Injurious to the Hop in New York 



185 



the insect being red with the exception of the fourth antennal segment. (The description 
is for the most typical specimens.) 

Second stage (fig. 35). — Length 1.9 mm.; general color slightly darker; median line broader 
and more distinct; clay-colored border patches indistinct; bands on antennae and legs more 
prominent; white spots beginning to appear around setae on abdominal segments; basal 




Fig. 34. 



FIRST-STAGE NYMPH OF HOP RED- 
BUG. X ABOUT 20 



Fig. 35. second-stage nymph of hop 
redbug. x nearly 15 



antennal segment a darker red and much more hairy; terminal segments lighter except at 
tip. Aberrant specimens showing no median line, no white bands, faint bands on antennae 
and legs, or faint bands on antennae and none on legs. 

Third stage (fig. 36). — Length 2.5 mm.; general color same as that of preceding stage; 
red bands on antennae and legs much darker than body; wing pads beginning to show; 





Fig. 3G. third-stage nymph of hop 

REDBUG. X nearly U 



Fig. 37. 



fourth-stage n\'mph of hop 

REDBUG. X 9 



white spots around setae more distinct. Setae longer and coarser. Some aberrant specimens 
as in second stage. 

Fourth stage (fig. 37).— Length 3.1 mm.; general color as in third stage; wuig pads brown- 
ish and reaching nearly to third abdominal segment; antennal segments thicker in red areas 
than in white; dusky spot showing around gland between third and fourth abdominal segments. 
Aberrant specimens as in preceding stages. 



ISt) 



1. M. Hawlky 



4 



Fifth stagr (fi^. •J*^'. — IxMiRth 4 nun.; a wide variation in Cdlor, some specimens being 
linht red with aIino«t transparent winn pads, others dark red with wiiiR pads an<l dark spota 
of legs sepia; wing pads reaching almost midway U-tween fourth and fifth ahdoininal seg- 

nu'iits; dusky spot around gland more promi- 
nent; in some cjises two dark splits on prono- 
tum; white spots around setae very dis- 
tinct. A wide variation in markings, as in 
earlier stages. 

The adult 
The adult rodbug is about milli- 
metois in IcuKth. In color it ranges 
from fusco-piceous to piccous, with 
the honiolytia sordid hyaline or pale 
j't'llowir^h and 
the e u n o ii s 
reddish. The 
pubescence is 
sparse. 




Fig. 38. 



FIFTH-ST.\GE NYMPH OF HOP RED- 
HI G. X 7 



LIFE HISTORY AND HABITS 

The egg 

The eggs of Paracalocoris hawleyi are inserted 
singly', and in groups of t\vo, three, or four, in the 
l)ark or the wood of hop poles, to which they are 
attached by a secretion. In cbdar bark the eggs 
are placed in a slit in the bark tiansverse to the 
grain, and can best be seen when the bark is torn 
lengthwise (fig. 39). When found in this way, the 
otherwise inconspicuous white cap may be located 
on the outside. Only one egg has been found in 
the hard wood of a jwle, and this was in a crack just 
deep enough to hold it. Since nymphs are equally 
common in the spring on the ccsdar bark poles 
and on the wooden poles, eggs must be laid here in 
large numU-rs. The egg stage lasts from nine to nine and one-half months. 




Fig. 39. eggs of hop 
redbig inserted in 
bark of cedar hop 

POLE. X 9 



Thi nymph 
The nymphs are active, and when disturl)ed they crawl rapidly among 
the leaves and vines and into the cracks of the hop poles. At rest they 



Insects Injurious to the Hop in New York 



187 



may usually be found on the undersides of the tenderest leaves, there 
being often from five to ten nymphs on a leaf and one hundred or more 
to a hill. When jarred they drop straight down to a lower leaf, to which 
they often adhere by everting the end of the alimentary canal. They 
prefer the tender leaves and vines, and therefore in August are more 
numerous near the tops of the poles. 
The data on four specimens bred in the year 1915 are given in table 11 : 

TABLE 11. Dates of Transformation and Length op Stages, 1915 



Specimen 


Date 

when 

egg was 

taken 


Date of 
hatching 


Date of beginning of nymphal stages 
after first 


Date 
when 
adult 
stage 
began 


Number 
of days 




Second 


Third 


Fourth 


Fifth 


egg to 
adult 


1 

2 

3 

4 


May 21 
May 21 
May 6 
May 6 


June 13 
June 13 
June 15 
June 10 


June 19 
June 19 
June 20 
June 15 


June 21 
June 21 
June 24 
June 22 


June 30 
June 30 
June 30 
June 30 


July 8 
July 6 
July 6 
July 7 


July 14 
July 13 
Julv 13 
July 12 


31 
30 
28 
32 



Average, 30.2 days. 



The specimens were bred in pctri dishes in a well- ventilated, unheated 
field laboratory. Pieces of bark containing eggs were placed in the dishes. 
These w:ere examined, and after 
hatching fresh food was added, each 
day. 

The adult 

The adult when disturbed drops a 
short distance and then flies gradually 
downward in a zigzag course. Adults 
may be found at rest on the vines, 
on the poles, and on the upper and 
under surfaces of the leaves. Techni- 
cal descriptions of the species and of 
four varieties have been pubhshed 
by McAtee (1916), who examined 
material sent him by H. H. Knight. 
Of these four varieties, Paracalocoris 
hawleyi var. hawleyi and P. hawleyi var. ancora (figs. 40 and 41, respec- 
tively), are the common forms on the hop. The former has a pale lateral 




Fig. 40. ADULT of one variety (hawleyi) 
OF hop redbug. X 62 



188 



I. M. Il.WVLKY 



% 



stripe oil llic cniiuiii, which is not present on the latter. The latter 
variety is imich more numerous than the former. 



SEASONAL HISTORY 

Overwintering ep;p;s of Paracnlocoris' 
luudcyi are laid in hop poles from the 
middle of August until September, as 
deteiinined by dissected adults. These 
hatch the following year from June 1 
up to nearly the first of .luly. The 
nymphal period lasts for about thirty 
days, adults beginning to appear about 
the first of July. Nearly all are winged 
by the first of August. Adults may 
often be found in September but there 
is no evidence that these survive the 
winter. 




Fig. 41. adilt ok another variety 
{aticora) of hop redbug. X 6j 



NATURAL ENEMIES 

The pentatomid Apateticus maculiverdris Say is predacious in both the 
nymphal and the adult form on the immature stages of the hop redbug. 
Eggs and nymphs of this species are common in hopyards in July and 
August. 

One of the Nabidae, RrdiiriolHs suhcnleoptratuK Kirby, which is present 
on many plants near the hopyards, has been found feeding on nymphs 
of the hop redbug. 

.\ predacious red mite, Trombidium sp., has been observed on several 
n3'mphs. 

PREDACIOUS HABIT OF THE HOP REDBUG 

Adults of Pnracalocon'.s hawleyi have been found fe(>ding on nymphs 
of their own kinil. Nymphs have been found also feeding on the pupae 
of Nemalommpa linibuta Haworth (Geometridae), the larvae of Lycia 
cognnttiria (luen^'e (Geometridae), the larvae of Hypena hitmuli Harris 
(Noctuidae), and the pupae of Malacosoma americana Fal). (Lasio- 
campidat;). 



I 



Insects Injurious to the Hop in New York 189 

CONTROL 

In 1915 it was decided to test a tobacco extract spray as a control measure 
against the hop redbiig. To this end nicotine sulfate, 1 pint to 100 gallons 
of water with 6 pounds of soap added, was applied on July 17. The 
material apparently killed the bugs at once. However, as 56 live nymphs 
were found on six sprayed hills, another spray was applied on July 19. 
This time Black-leaf -40, 1 pint to 100 gallons of water with 4 pounds of 
soap, was used. On July 20 six hills had 16 dead and 11 Uve nymphs 
present, but on July 21 no dead nymphs could be found. This is due 
to the fact that after the spray material dries, the nymphs drop off. The 
following experiment shows that whenever nymphs are reached they 
are killed. On July 19, when the field experiments in spraying were 
made, 40 sprayed specimens were placed in a laboratory cage, none of 
which revived. Thirty specimens sprayed with an atomizer were all 
killed by the same solution as was used in the field. 

Since nicotine sulfate, f pint to 100 gallons of water with 4 pounds 
of soap, will control the hop aphis (Phorodon humuli Schrank), the 
writer tried it to ascertain its effect on the hop redbug. Leaves with 
redbugs from vines sprayed in the field were taken into the laboratory; 
of 15 specimens, 6 were alive on the following day. Of 30 redbugs sprayed 
in the laboratory, 7 were alive twenty-four hours later. Bugs that 
became attached to the glass dish by means of the solution were invariably 
killed; those not attached often recovered. To prevent sticking, filter paper 
was placed in the bottom of the dish and the bugs were sprayed with 
an atomizer. Of 10 treated in this way, 6 were killed. It is evident 
that this strength is insufficient for the control of the redbug. 

To be successful, spraying should be done about the third week in 
June, before the vines have produced lai'ge arms. Most of the nymphs 
will have hatched and can be reached easily at this time. Later, when 
the vines have become dense and many have slipped down the poles, 
it is impossible to reach all the bugs hidden among the mass of leaves. 
Poles as well as vines should be drenched, since many nymphs take refuge 
in the cracks and under projecting bark. Because of the agility of the 
bugs, it is wise to spray a hill from opposite sides at the same time when 
possible. Winged forms fly before they can be reached by a spray. 



100 I. M. Hawley 



THK HOP SNOUT-MOTH 
(Hypena humuli Harris) 
The larva of the hop snout-moth was recorded in 1841 as a leaf-eating 
pest. It is widely distributed, occurring in most parts of the United 
States and southern Canada. So far as known it feeds only on the hop, 
and thus its distribution tends to follow that of its host (Howard, 1897). 
It li:i.>< not been reported as a .serious pest on the Pacific coast. As a rule 
the injury that it causes is not great, but at intervals the larvae of the 
second brood occiu- in such large numbers as to strip the hop vines of 
their leaves. The writer has found occasional hills in 
(his condition but there has not been a general out- 
break of the insect in the past five years. 



i 





DESCRIPTION 

The egg 
Fig. 42. egg of The egg of Hjjpenn hunnili (fig. 42) is from 0.5 
Hop^sNouT-MOTH. q^ luiWimoiiiv iu' diameter. In color it is pale yellow- 
white. The form is circular, slightly dome-shaped, 
flattened below. The surface Is vertically riilged and grooved. There 
are apparently eight primary ribs converging at the micropyle end, with 
two or three secondary ribs between each pair of primaries. The micro- 
pyle is slightly flattened and irregularly 
reticulated. 

The larva 
The larva (fig. 43) is from 20 to 25 Fig- 43. full-grown larva of 

.... • 1 1 rr<i 11 HOP SNOUT-MOTH. SLIGHTLY 

millimeters in length. The color is pale enlarged 
green, marked by a median longitudinal 

dark line and a prominent dorso-lateral white line with a fainter white line 
in the region of the spiracle. The head as well as the body bears promi- 
nent black tubercles. There are four pairs of prologs including the anal 
prolegs. 

Thi- ])npa 

The pupa is from 11.") to 12..') millimeters in length and 8.5 millimeters 
in greatest diameter. The body is dark brown, glos.sy, and faintly clothed 
with hairs. The cremaster consists of two large, outwardly pointing 



I 



Insects Injurious to the Hop in New York 



191 



hooks at the tip, with two smaller ones on each side. The ventral side 
bears a fourth pair of hooks. 

The adult 

The adult (fig. 44) is described as follows by Dr. W. T. M. Forbes: 

The fore wing of the female is Ught wood brown, with a smoky gray trapezoidal patch 
resting on the inner margin rather before the middle; the base of the fore wing is more or 




Fig. 44. adult female of hop snout-moth on 
A hop leaf. X 2 

less darkened, and there is a dark shade on the outer margin, below a blackish streak which 
runs down obliquely from the apex; four small black tufts outline the trapezoidal patch; 
the usual noctuid markings are present, but are obscure, except for a row of black dots before 
the outer margin, representing the st. line. The hind wings and the body are similarly 
colored, without distinct markings. The palpi extend straight forward and are as long 
as the thorax, and with a tuft of hair on the face they give the appearance of a beak; the 
terminal joint is short and upturned. The inner margin of the fore wing is nearly straight 



I 



102 



I. M. Hawley 



(unlike the clover Hypena, Plathi/pcna scabra). The male is similar, but the fore winRs 
are even dull gray, with all the markings obscure. The male is slightly larger than the 
femafe. Spread 25 to '.iO mm. 

UFE HISTORY AND HABITS 

The egg 
The eggs of the first brood of Hypena hurmdi arc dopo.sited among the 
hidrs on the underside of the hop leaf (fig. 45) (hning ]\Iay. at which time 




Fic. 1.'). i:or. of nop snout-moth on i.e.\f. X 2^ 



the hops are only a few feet above gioiind. Eight eggs have been found 
on one folded leaf. These eggs, which are laid In* overwintering females, 
may not hatch for three weeks; the exact length of the egg stage is not 
known. Al)Out two days before hatching, the eggs turn dark and the 
young larvae may be seen within. Eggs have been foimd in the field 
from May to June 7. 

The eggs of the seconil txood also aic <l('i)osit('(l on the leaves. In 
some cases they are laid on the older leaves near the ground, but theyJ 



Insects Injurious to the Hop in New York 



193 



may be found on tender leaves near the top of the pole, 
second brood have been found from July 28 to August 11. 



Eggs of the 



The larva 

The larva is a semi-looper, and when disturbed often throws its head 
in the air hke a geometer. At rest it may be found stretched at full 
length on the underside of a leaf. Its color so protects it that it may 
be easily overlooked (fig. 46). When disturbed it moves its body 




Fig. 40. full-grown l.'^rva of hop snout-moth on leaf, natural size 



l)ack and forth with a wriggling motion, and drops by means of a thread. 
It may sometimes be found suspended in the air by this means. A newly- 
hatched larva (fig. 47) rarely eats thru a leaf in feeding, but when 
a few days older it eats out a clean-cut hole either on the margin or in the 
central part of the leaf. Full-grown larvae of the first brood have been 
taken from June 17 to July 21, and those of the second brood from August 
15 to September 6. 

In these experiments breeding was carried on in a field laboratory. 
In 1914 leaves were placed in jars of water antl covered with a lamp 



194 



I. M. Hawley 



chimney. In 101') larvae were kept in petii dishes to whieh a fresli leaf 
was added eaeh day. The breeding; records of KM I and I'.lj.") are jz;iven 
in tables 12 and l.'i 




Fig. 17. vocng i..\rv.\ of hop snout-moth on leaf, with 
kkcenti.y shkd skin. x aboct o 



TABLE 12. Dates ok Tkansformation and Length of Stages of First Brood, 1914 



Specimen 


Date 

when 

egg was 

taken 


Date of 
hatching 


Dates of molts 


Date 
when 
pupal 
stage 
began 


Date 
when 
adult 
stage 
began 


Number 

of days 

from 

egg to 

adult 


1 


May 26 
May 20 
May 2() 
Mav 26 
May 26 
Mav 20 


May 28 
May 28 
Mav 28 
Mav 28 
Mav 28 
May 28 


June 1, 6, 11 
June 1. 5, 11 
June 1, 5, 12 
June 1, 5, 11 
June 2, 6, 14 
June 2, 6, 14 


June 16 
June 23 
June 23 
June 24 
June 23 
June 25 


July 1 
July 5 
July 6 
July 7 
July 6 
July 7 


34 


2 


38 


3 


39 


4 

5 


40 
39 


G 


40 



Average — l.Arval stage, 2.J.3 days; pupal stage, 13 days; egg to adult, 38.3 days. 



Insects Injurious to the Hop in New York 



196 



TABLE 13. Dates of Transformation and Length of Stages of First Brood, 1915 



Specimen 


Date 

when 

egg was 

taken 


» 

Date 

of 

hatching 


Dates of molts 


Date 

when 

cocoon 

was spun 


Date 
when 
pupal 

stage 
began 


Date 
when 
adult 
stage 
began 


Number 
of days 

from 
egg to 

adult 


1 


May 6 
May 6 

May 28 
May 28 
May 21 
June 7 


May 18 
May 21 
June 7 
J. me 8 
June 13 
June 13 




June 18 
June 21 

July' "7 
July 7 
July 11 


June 21 
June 23 
July 5 
July 8 
July 9 
July 12 


July 8 
July 8 
July 17 
July 21 
July 21 
July 26 


51 


2 




48 


3 




40 


4 




43 


5 

6 


June 17, 26, 30 
June 17, 23, 30 


38 
43 



Average — Larval stage, 30 days; pupal stage, 13.8 days; egg to adult, 43.8 days. 



The pupa 

There has been much disaj2;reement as to the manner and place of 
pupation of the hop snout-moth (Howard, 1897), arising from the large 
variety of conditions under which the process may occur. The writer 
has found naked pupae on the surface of the soil or just beneath the 
upper layer of dirt, or 
attached to leaves and 
hop poles by a few strands 
of silk (fig. 48). Inclosed 
pupae have been found 
fastened in cocoons in a 
single rolled leaf and be- 
tween two leaves. They 
have been found also on 
hop poles, on dead vines, 
and in dirt. The cocoon 
may be frail or heavy. 
A. cocoon found in the 
ground was covered with 

small particles of dirt. Pupae of the second brood are usually found 
naked and in the ground. Pupae of the first brood have been found 
between June 16 and July 26, and those of the second brood between 
August 19 and September 16. 




Fig. 48. 



PUPA SKIN OF HOP SNOUT-MOTH ATTACHED 
TO LEAF. X 24 



190 I. M. Hawlet 



2 



riir adult 

The adult of Hypenn humuli has l)ecn taken in the spring and late 
in the fall. All pupae under «)l)servation have transformed to moths 
in Sej)teinl)er or October, and thus it is evident that the insect hibernates 
in the adult stage, 

SEASONAL HISTORY 

The life history of Ihjpena humuli may vaiy greatly, depending on 
weather conditions and the date of emergence of the moths from hiber- 
nation. The following is the normal life cycle. Eggs are laid about the 
middle of May and hatch in about two weeks. The larvae become full- 
grown by July 1, the larval stage lasting about one month. The pupal 
stage covers about thirteen days and adults emerge about the middle 
of July. Eggs of the second brood are laid in from one to two weeks, 
and the.se hatch the first week of August. The larvae are full-grown at 
hop-picking time, early in September, when they pupate. Moths come out 
during the latter half of September and seek hibernating quarters. 

NATURAL ENEMIES 

Nymphs of Parncalocoris hawlejii and adults of Reduriohis .mbcohoptratus 
Kirby are both occasionally predacious on the larvae of Hypena humuli. 

Masicera rviila Mcngn.,^ a tachinid fly, was bred from a snout-moth 
larva in 1914. A larva taken into the laboratory on July 6 started to 
spin its cocoon on July 11 and the parasites emerged from the cocoon 
on August 4. In the summer of 1915, the parasite M. eufitchiae Towns.*" 
also wjis bred from a snout-moth larva. 

Howard (1897) rejwrts Exori.stn hypenae also as a parasite on the larva 
of Hypena humuli. 

CONTROL 

During the pa.st three years no opportunity occurred to test control 
measures against the hop snout-moth. It has been reported that powdered 
arsenate of lead mixed with the sulfur used for the hop mildew, in a ratio 
of 1 to 10, has been found effective. If spraying is practiced for the hop 
aphis, the addition of arsenate of lead to the nicotine sulfate spray 
should prov(! a satisfactory control measure against the hop snout-moth 

» Determined by <) A. Juhanniten. 



Insects Injurious to the Hop in New York 197 

THE FILAMENTED LOOPER 
(Nematocampa limbata Haworth) 

The larva of the filamented looper has been found as a leaf-eating 
pest of the hop in large numbers near Sangerfield, New York. It is 
not restricted entirely to this region, however, a few specimens having 
been found in some hopyards thirty miles away. The species is a general 
feeder, having been reported from currant, birch, stonecrop, plum, apple, 
crab apple, oak, and hazel, and on strawberry under the name strawberry 
looper (Packard, 1876, and Lugger, 1898). It may have come to the 
hop in the form of eggs on the cedar hop poles; but more probably it 
has migrated from other plants, as many of its known hosts occur in the 
region. It is widely distributed in the eastern part of this continent, 
being reported from Canada, New England, Minnesota, Georgia, and 
Illinois (French, 1878, and Lugger, 1898). While it is not of great 
economic importance at the present time, its numbers are increasing 
and it may become a serious pest. 

DESCRIPTION 

The egg 
The egg of the filamented looper is about 0.4 millimeter in length, 
0.2 millimeter wide, and 0.1 millimeter high, or of the horizontal type. The 
color is pale green when the egg is freshly laid, turning in from twenty- 
four to forty-eight hours to a dull tomato red. The egg is oblong, truncate 
and shghtly depressed at the micropyle end and rounded at the opposite 
end. The surface bears faint, hexagonal reticulations. 

The larva 
The larva passes thru four stages, which may be described as follows: 

First stage. — Length (one day) 1 mm.; alternating tomato red and faint greenish white 
crossbands; head of a brown tint. One pair of pro legs and anal pro legs. 

Second stage. — Length 4 mm. (average of five specimens); abdominal red bands more dis- 
tinct; anal end suffused with red. Small tubercles appearing for the first time on second and 
third abdominal segments. 

Third stage. — Length 9 mm. (average of five specimens) ; filaments at least equal to di- 
ameter of body in length; markings similar, but a variation occurring as in fourth stage. 

Fourth stage. — (Detailed description of full-grown larva.) Length 18-20 mm.; color 
variable; general color gray, but some forms having a prominent tinge or oblique markings 
of shades of green, yellow, or brown. Body cylindrical. Head mottled, large, full on each 



198 



I. M. Hawley 




Fig. in. 



ADULT MALE OF 
LOOPER. X 25 



KILAMENTED 



side and flatteiu-d in front. First uhdoininal .st^nmeiit brarinR a sub-acute tubercle; second 
and third sennifiit-x haviuK a pair of loiiK. Hexible filaments of the .same color a.s the body; 
tho-s*' of the second seument, which are white-tipix'd, reaching the head when extended 
forward; tho-st' of the third seRmeiit al)out two-thirds as long as tho.M,- of second .segment; 
two small tuliercles caudad of each of these appendages, and back of tho.se of the first 

two abdominal segments two light yellow 
.spots; median dark line running from the 
head to the first pair of filaments in dark 
forms; eighth abdominal .segment Ijearing a 
pair of medianly joined tubercles, appearing 
from the side as a fleshy hump; just caudad 
of the humji and runnins to the end of the 
anal shield, a dark area bordered by yellow; 
a lateral lighter area present above and be- 
tween the two pairs of prolegs. 

The pupa 

The pupa is from 10 to 11 milli- 
metors lonp;. It is gray or pale 
yoUow in coloi-, and is niotflcHl except for the membrane between the 
abdominal segments. The cremaster consists of two pairs of terminal 
outwardly curvinp; hooks, one large and one small, and a third pair of 
liooks just before the apex. 

Tlw (idult 

Th(> adult (figs. 49 
and oO) is described 
as follows by Dr. 
^^■. T. M. Forl^es : 

Male straw yellow, fe- 
male cream white. Fore 
wing with three even 
brown lines; t.a. line ex- 
curved, especially over 
cell; inner t.p. line ex- 
curved beyond cell and 
slightly at fold, outer t.p. 

incurved at pt)ints where inner is excurved and in some ca.ses meeting it at those points; 

outer third of wing brown on inner half in male and everywhere but at apex in female; 

fringes brown. Hind wing similar, without t.a. line and with brown area more extensive; 

veins more or less bnjwn, especially in female. Spread 1!) 2.j mm. 




I.MALE OK FILAMENTKD LOOI'ER. 



LIKE HISTORY AND HAHITS 
The C(J(J 

The eggs of the filuMieiiled looper are attached by a secretion und(>r 
the edge of projecting bark, or tucked in cracks of tiie hop poles, and 



Insects Injurious to the Hop in New York 



199 



arc found singly, a fow in a place, or in irregular masses (figs. 51 and 52). 
The writer has found fifty or more eggs on a cedar hop pole by removing 




Fig. 51. eggs of 
filam e n ted 
looper under 
projecting 
edge of bark 
of a cedar hop 

POLE. X 8 




Fig. 52. eggs of filamentkd looper on 
a sliver of a cedar hop pole. x 5 



the bark and inspecting the crevices. Overwintering eggs are laid in 
August, and hatch from the middle of May until late in June of the fol- 
lowing year; the egg stage is therefore about ten months. Two females 
under observation laid eggs as indicated in table 14: 

TABLE 14. Data on Egg Laying by Two Moths, 1915 



Specimen 


Date when 
female 
emerged 


Date when 
first eggs 
were laid 


Number of 
eggs found 
on August 

28 


Date pre- 
ceding which 
moths died 


1 


August 15 
August 18 


August 23 
August 25 


25 
16 


September 8 
September '8 


2 





The larva 

The larva moves with a looping motion (fig. 53), and when disturbed 
it assumes an erect attitude and projects its filaments to the Umit. It 



2(X) 



1. M. Hawley 



ina>- also drop liv a thread and hang in mid-air; sixty suspended larvae 
have Ix^en counted on one liill after the pole had been shaken. The hirva 

feeds oftener on the margin 

of the leaf than in the central 
part. The veins of a leaf are 
often eaten thru in such a 
way that the leaf dies at thatl | 
point and a dead crumpled 
area on tlie margin remains. 
A larva, perhaps for protec- 
tion, often a-ssumes a posit ioni 
resembling this dead part of 
the leaf. Full-grown larvae 
have been found from June 25 
until August 18. Six speci- 
mens were bred in petri dishes 
in the summer of 1915, as 
indicated in table 15. 

The pupa 

The change to the pupal 
stage takes place in the cracka 

of hoji jioles, in leaves curled 
and fastened with a few strands 
of silk, or when the larva is 




l''lO. 53. LARVA OK FILAMENTED LOOPER. X 2.J 



attached by silk flat against an uncurled leaf. Often the pupa is attached 
by a few strands of silk and hangs free from a leaf or a vine (fig. 54). In 

TABLE 15. Dates of Transformation and Length of Stages, 1915 



Specimen 


Date 

when egjt 
wa« 
taken 


Date of 
hatchiuK 


Dates of molts 


Date when 

cocoon 
was spun 


Date when 

pupal 
stage began 


Date when 

adult 
stage began 


Number of 
days from m 


1 




June 28 
June ft 
Julv 1ft 
July 20 
July 7 
July 5 


July ft, 9. 13 




July 2.1 
Julv 1ft 

AllKU^^t It 

August 13 
August 2 
.August 3 


August 7 
July 29 
August 28 
August 27 
.Vugust 15 
August 15 


40 


2 


May ft 
May ft 
May 12 
May 21 
May 21 




53 


3 


Julv 21. 25, August 1 
July 24.2<.», August 4 


August 11 
August 11 


43 


4 


38 


5 


39 









41 



*«in> Ai •fiiiy «i • ■ .luifUDb o /lUMuo 

Average — Larval staffo, 28.K dayft; pupal staice, 13 5 day»\ egg to adult, 42.3 days 



Insects Injurious to the Hop in New York 



201 



many cases small pieces of dead leaves arc curled around the pupa. Pupae 
have been found from June 27 until August 28. 

The adult 
The brightly colored moths are common in August in the hopyards. 
They rest flat on the ground and on the lower leaves, with their wings 
half spread. The sexes are 
about equal in number. 

SEASONAL HISTORY 

The Ufe history of A'^e- 
matocampa limhata varies 
greatly, depending on the 
time of hatching of the 
eggs. A typical life history 
is as follows: 

The eggs, which are laid 
on hop poles in the latter 
part of August, hatch the 
last of the following June. 
The larvae become full- 
grown the last of July, and 
enter a pupal stage which 
covers two weeks. Adults 
appear the middle of August 
and begin to lay eggs in 
about one week. There is 
one generation a year. 

CONTROL 

The control measure sug- 
gested for the hop snout- 
moth should hold the filamented looper in check also. On July 17, 1915, 
several infested hills were dusted with powdered arsenate of lead and sulfur 
in a ratio of 1 to 10. When the hills were examined later some Uve 
larvae were found. Since rain followed soon after the application, how- 
ever, the test was not a fair one. 




Fig. 54. pupa of filamented looper. X 4 



202 



I. M. Hawley 



THE HOI' APHIS 
{Phorodoii humuli Schrank) 

The hop aphis, Phorodon hunnili (figs. 55 and 56), is a pest wherever 
hops are grown. Il lias Ik'cmi known in New York State since 1863 at 

least (Parker, 1913), and in some 
years has caused an almost total loss 
of the crop. As the insect has been 
extensively studied on the Pacific 
coast, the writer has limited his work 
on the species to observations on its 
seasonal history and habits in New 
York State, and to the application of 
some control measures under New 
York conditions. 




FlO. 55. WINGLESS VIVIPAROUS FEMALE 
OF HOP APHIS. ENLARGED 



SEASONAL HISTORY 

In the eastern United States the 
hop aphis has been found to winter 
only in the egg stage on plum. Clarke (1904) reports that in C'aliforni 
the aphides winter on hop roots. In order to obtain some eviden 
on this point for 
New York, the 
writer removed 
the dirt from 
three hills, 
placed vines cov- 
ered with the 
insects around 
the hop roots, 
and then cov- 
ered the hills. 
On examination 
the following 

spring, no signs of live aphides or of their eggs could In* found in these 
hills. Additional evidence is furnished by the fact that migratory aphiiles 
have always appeared on the hop before the wingless forms. 




Fig. .5fi. winged vivipakol's female of hop aphis, enlarged 



Insects Injurious to the Hop in New York 



203 



Altho Riley (Riley and Alwooci, 1889) reported the third generation 
as the one that produces winged forms in New York, it is probable that 
some winged forms are produced in the second generation. On May 21, 
1913, full-grown lice and recent offspring were found on a plum tree near 
Sangerfield. On most of the leaves there was one full-grown louse, but on 
one leaf there were five. 
Some of the young of 
these forms had wing pads 
on the 4th of June. If 
those first found were of 
the first generation, the 
second generation pro- 
duces winged forms, the 
same as in the Pacific 
hop region. Some insects 
of the third generation 
also are winged. In fact, 
the writer has found 
winged forms being pro- 
duced on a plum tree 
under observation thru 
July and August, but, for 
unknown reasons, after 
the June migration there 
have been but few winged 
forms on the hop The 
height of the return mi- 
gration occurs during hop 
picking, about the first of 
September. 

On the hop the winged 
insects are found on the 

underside of the topmost leaves (fig. 57), there being from one to twenty 
or more to a leaf. The wingless descendants from these also five on the 
underside of the tender foliage. In August, when the lice are numerous, 
full-grown forms are occasionally found along the veins on the upper side 
of the leaves. When the young hops are formed, hce migrate to them in 




Fig. 57. 



WINGED VIVIPAROUS FEMALE OF HOP APHIS 
ON A LEAF. ENLARGED 



204 



1. M. IIawlkv 




large iiuinbers. The writer hiis noted younp; lice in hop cones when the 
leaves were comparatively free from the insects. 

Two sjX'cies of ants have been found associated with the hop aphis — a 
large species, Formim fusca var. suhsericai Say; and a small form, Pre- 

nolepia imparis Say.* 

NATURE OF THE INJURY 

The injuiy to the hop caused 
by Phorodon humuli is of two 
kinds: (1) the woakening of the 
\ ines and the stunting of the 
hop cones due to the constant 
r(Muoval of sap; and (2) the 
coating of the hops with honey- 
dew in which a fungus, Clado- 
sporium, grows. 

The feeding of the aphides 
on the leaves and the vines so 
weakens the plant that it is 
common to find hills in which 
the vines have not climbed 
above the string. The vines 
are dwarfed and the hop cones 
are small, with sickly, scraggly 
bracts (fig. 58). This condition 
is found when the aphides attack 
the hill in numbers early in the 
sinison. 

When the lice become nu- 
merous (fig. 59) the leaves glisten 
with the honeydew which they 
excrete. The entire surface of the vines and the leaves is coated with 
this excretion. When the lice enter the cones the bracts also are covered., 
The greatest damage is caused when the lice enter the full-grown ho) 
just before picking time. They coat the hojis with the honeydew, causing 

* Both npeciea determined by W. M. Whoclcr. 



Fig. 58. above, hops injured by the hop 
aphis; below, healthy hops, about one- 
half NATURAL SIZE 



1 



Insects Injurious to the Hop in New York 



205 



the bracts to lose their crispness and making them stick together when 
pressed between the fingers. 

The fungus Cladosporium grows in the honeydew and gives the hop 
a soot-covered appearance. This greatly injures the quahty and makes 
the hops unsalable. Among hop growers it is spoken of as black mold. 
Many yards in New York were injured in this manner in 1915 and the 
hops were not picked, while hops from some yards that were picked are 




Fig. 59. wingless hop aphides on a hop lem-. X about 5 



still unsold. The lice are much more numci'ous in warm, moist seasons. 
In 1915 the rainfall records taken showed 5.49 inches during June, 7.64 
inches during July, and 9.28 inches during August. This is much above 
the normal for these months. A wet spring followed by a long, dry 
period is not so serious as continued rains near harvesting time. Under 
the latter condition great loss may result in a few weeks, owing to the 
increase of the lice, the great production of honeydew, and the growth 
of the black mold. 



200 



1. M. IIawley 



NATURAL KNKMIES 

Predatory enemies 'j^B 

The following predatory insects have been collected feeding on the 
hop aphis: 

Coleoptera Family 

Adalia hipunctata Linn Coccinellidae 

Ilippodnmid courer(jens Guer. (lady beetle, figs. 60 and 61) Coccinellidae 

Cocci ncUa (rifasciata Linn Coccinellidae 

Coccinella 9-noiata Herbst Coccinellidae 

CoccineUn mnguinea Linn Coccinellidae 

Hippodaniia parenthesis Say Coccinellidae 

Anatis 15-punciata Oliv Coccinellidae 

Neuroptera 

Chrysopa oculata Say ^ (aphis lion, fig. 62) Chrysojiiflae 

Hctncrobius stiyiuatcrus Fitch ^ Henicrobiidae 

Dipt era 

Syrjdnis ainericamis Wiedemann^ Syrphidac 

AUoijrapta obliqwi Say * Syrphidac 




Fig. 



60. LARVA OF LADY BEETLE ON A HOP LEA!-. 
X ABOUT 2 



Parasites 

One parasite has been 
bred from the hop aphis 
— Praon sp.," of the order 
Hymcnoptera, family 
Braconidae. 

SPKAYIXG AND CONTROL 
EXPERIMENTS 

The spiaying operations 
for control of the hop 
aphis undertaken by 
writer. These are here 






growers during 1915 were observed by the 

described, and some original data on spraying and dusting are given. 

■ Delpmiinml by R. C. Smith. 

• Detonnined by O. A. JohniinHcii. 

• Determined by A. B. Gahan, thru the kindness of Dr. L. O. Howiinl. 



Insects Injurious to the Hop in New York 



207 




Fig. (1. KGGs OF lady beetle on a hop leaf, enlarged 



The first spraying of the season was done on the Louie farm, at Schuyler 
Lake. The material used was nicotine sulfate (Black-leaf-4G) in a solu- 
tion of 1 gallon to 
2000 gallons of 
water, with whale- 
oil soap added, 4 
pounds to 100 
gallons. A Friend 
pony outfit (fig. 
63), with three 
leads of hose, was 
used. Two men, 
with 6-foot poles, 
30°-angle nozzles, 
and 15 feet of 
hose, covered two 
rows each, and the 
third man, going 

behind, covered the high arms and the tops of the poles. Calyx nozzles 
of the Vcrmorel type, throwing more than the usual quantity of material, 
were used. The tank had a capacity of 150 gallons, and with a H-horse- 
power engine a pressure of over 150 pounds was maintained. The cost for 

spraying two acres a day was as 
follows: four men, S8; one horse, 
SI; 800 gallons of spray material, 
$6; total, S15 for two acres, or 
$7.50 an acre. Hops of a fine 
quality were produced. 

Under the direction of F. M, 
Blodgett, about ten hopyards 
were sprayed. In one yard, near 
Waterville, a pressure of 165 
pounds was maintained and 600 
or more gallons of spray material 
were used to the acre. In all 
cases nicotine sulfate (1-2000) and whale-oil soap (4-100) were used. 
During these operations the writer picked sprayed leaves and made counts 




Fig. 62. aphis lion, the larva of which is 
predacious on the hop aphis, enlarged 

(Photograph by H. H. Knight) 




Fig. 63. sprayer lsed on the lolie farm — a common type 

to test the effectiveness of th(^ sjiiaA'. The results of these counts are] 
Riven in table 10: 



TABLE 


16. Results of Spraying 


Experiments with Black-Leaf-40, 1915 


Yard 


Date of 
spraying 


Date of 
count 


N umber 
of lice 
found 


Number 
dead 


Per cent 

of 
control 


Number 

of 
leaves 
used 


Kcniarks W 


Hatch 


July 27 


July 28 


830 


821 


98.9 


20 


All lice counted 


Hatch 


August 18 


August 19 


108 


100 


94.3 


12 


Only full-grown lice 
counted • 


Hatch 


August 19 


August 20 


356 


352 


98.9 


12 


Only full-grown licafl 
counted 


Hewett 


August 31 


September 2 


721 


698 


96.8 


20 


All lice counted 



Sulfur is used by throwers to control the Jiop mildew, and so the writer 
tried eoinbinatioiis of sulfur with nicotine sulfate, usiiifi different stickei-s, 
to see its effect on the lice, payiiif^ no attention to the control of the hop 
mildew. The results are given in tal)le 17: 



Insects Injurious to the Hop in New York 



209 



TABLE 17. Results of Experiments to Test Black-Leaf-40 with Sulfur in Various 

Forms, 1915 

(Only full-grown lice were counted. B.L.40== BIack-leaf-40, 1-2000; L.S = lime-sulfur 
1-40; Sp.= soap, 4-100; S = sulfur) 



Material used 


Date of 
spraying 


Date of 
first 
count 


Number 

of 
leaves 
used 


Number 
of lice 
found 


Number 
alive 


Per cent 

of 
control 


Date of 
second 
count 


Number 

of 
leaves 
used 


Number 
of lice 
alive 


B. L. 40, Sp., S 


July 16 


July 17 


12 


828 


11 


98.7 


July 24 


12 


4 


B. L. 40, L. S. 


July 16 


July 17 


12 


360 


16 


95.5 


July 24 


12 


30 


B. L. 40, L. S., 
Sp. 


July 16 


July 17 


12 


574 


3 


99.5 


July 24 


12 


4 


B. L. 40, Sp. 


July 17 


July 20 


12 


77 


2 


97.4 


July 24 


12 


1 



Lime-sulfur leaves a smeary coating and should not be used just 
before the hops are to be picked. None of the sprays tested injured 
the hops. 

There has been much demand among growers for a louse-killing material 
that can be applied in a dust form with the sulfur used for the hop mildew. 
With this in view an experiment was carried on in two parts. In one 
(W, table 18) the hills were sprayed with water and the material was 
dusted on; in the other (D) the material was apphed to the dry leav&s. 
Both the upper and the under sides of the leaves were well covered in 
each case. The results of these experiments are given in table 18: 



TABLE 18. Results of Dusting Experiments, 1915 
(Ten leaves of each kind were examined, and only adult lice were counted) 



Material used 


Date of 
application 


Date of 
count 


Number 
of lice 
found 


Number 
dead. 


Number 
alive 


Per cent 

of 
control 


Tobacco dust (W) 

(D) 


August 6 
August 6 


August 10 
August 10 


249 
125 


12 
4 


237 
121 


4.8 
3.2 


Tobacco dust and sulfur, 1-1 (W) 

(D) 


August 6 
August 6 


August 10 
August 10 


243 
86 


6 



237 

86 


2.5 
0.0 


Tobacco dust and flour, 1-1 (W) 

(D) 


August 6 
August 6 


August 10 
August 10 


138 
116 


57 
5 


81 
111 


41.3 
4.3 


Tobacco dust and soap, 3-1 (W) 

(D) 


August 6 
August 6 


August 10 
August 10 


128 
78 


80 
7 


48 
71 


62.5 
9.0 


Tobacco dust, sulfur, and soap, 2-3-l(W) 

(D) 


August 6 
August 6 


August 10 
August 10 


126 
49 


113 
3 


13 
46 


89.7 
6.1 



210 I- I^I Hawley 

It is evident that dusting was not effective. The tobacco dust, which 
was used as the killing; a^;eIlt, was useless even when the leaves were wet. 
A few aj)hides were stuck to the leaves by the flour when wet. The pow- 
dered soap, when wet, was efficient, but inasmuch as this soap costs 22 
cents a pound it cannot be considered practicable. Only a driving rain 
of long duration could wet the underside of the leaves, and with such a 
rain there would be a tendency for the lice to be washed off and a spray 
applied would be of little use. 

If the lice on the plum are killed, the infestation will be cut down. 
This cannot be considered as a sure control, because scrubby plum trees 
along fence rows are prolific breeding centers. The writer found many 
winged lice in one corner of a hopyard. In searching for the source he 
found a small jilum tree, less than three feet high and almost concealed 
by grass, completely covered with the pests. 

Lice are apparently carried long distances by the wind. Winged forms 
have been found in large numbers in yards where the owner declared 
there weic no plum trees within half a mile. A thoro search by the writer 
did not (Usclo.se the source of the infestation. It is po.ssible that some 
other host may exist, but none has been found, even tho many kinds of 
trees and bushes have been examined foi- lice of this species. 

Recommendation 

The following practice is recommended for control of the hop aphis: 
Spray the last week of June or the first week of July with nicotine 
sulfate (1-2000, or ^ pint t ) 100 gallons) and soap (4-100). Use a one- 
horse sprayer with a l')()-gallon tank and three leads of hose. Use two G- 
foot poles with 30°-angle nozzles and 15 feet of hose, and one longer 
pol(> without the angle and with 80 feet of hose. Let each of the men 
with the short poles cover th;' lower vines and arms of two rows, and let 
the man behind, with the long pole, cover thoroly the iiigher vines and 
arms (hg. 04). A Vermorel-type nozzle throwing a coaise spray is elH- 
cient, but a nozzle pro<lucing a mist spray is reconnnended on the 
Pacific coast. The soap should be melted in (juantity; a large iron ket- 
tle is convenient for this puri)ose. Tf the yarcl is distant from the water 
supply, a filling wagon is necessary. 



Insects Injurious to the Hop in New York 



211 



It is important to hit all lice. Those on the higher, tenderer leaves, 
where the winged forms collect and where the migration to the hop cones 
takes place, must be killed. Late spraying is ineffective, as some lice can- 
not be reached because of the growth of the arms and because some will 
have migrated into the burs and the hops. If all winged hce are killed 
early in the season, there will be none to reproduce later. 




Fig. 64. spraying hops with a power sprayer 

(Photograph by C. R. Crosby) 



Because of this pest, New York State in the past has lost hops which 
have cost thousands of dollars to raise. Spraying should be considered 
as crop insurance. While it will not result in saving a crop every year, 
it will improve the quality of the product and raise the price when the 
average quality is low. The history of the past few years proves that 
hop dealers want hops of a good quality, and that such hops usually sell 
readily and at an advantageous price. 



212 I- ^I- Hawlky 



THE RED SPIDER, OR SPIDER MITE 
{Tctranychus telariui^ Liiinaeu**) 

Tho rod spider occasionally appears in the hopyards of New York, l)iit 
has never caused any serious damage here sucii a-< it has on the Pacific 
coast. With the shorter growing season and the cold winters, it is not 
likely that it will become a serious pest. 

The mites were observed on weeds and hop poles on May 6, 1915, and 
it is probable that they hibernate mainly as adults in cracks of the 
poles or on dead weeds around tlu; yards. The presence of the mite may 
be detected by small, light yellow spots at the base of a leaf between the 
main veins. If the underside of such a leaf is examined, silken webs will 
ho found and beneath these the mites usually rest. Later the leaves turn 
yellow and a few drop off. The lower leaves are first attacked, and as 
the.se leaves are killed the mites move upward and some enter the hops. 
A few mites were fourul in the hops of on(; yard in the dry summer 
of 1913. 

CONTROL 

It has never been necessary to adopt control measures against the red 
spider in New York hopyai'ds. In 1913 a few hills were sprayed with 
flour paste (8-100), and others with Ume-sulfur (1-80) and flour paste 
(4-100), as recomuKuided by Parker (1913, a and b) in conseciuence of 
his work on the Pacific coast. The action of both materials was satis- 
factory, but, as neither spray kills the eggs and since only one ajiplica- 
tion was made, mites were present a few weeks later. Not all the mites 
were killed, as the mist spray which was used did not always penetrate 
the webs to the mites beneath. If desirable, flour paste or lime-sulfur 
may be applied in combination with the Black-leaf-lO used for control of 
the hop aphis. Black-leaf-40 with soot will kill many of the mites, and 
if used at a high pressure it might give control. 

THE HOP MERCHANTS 
{Folygonia interrogationis Fabricius and P. comma Harris) 

The chrysalides of the two well-known butterflies Folygonia interroga- 
tionis and /■*. comma are called hop merchants, and are familiar to growers 



Insects Injurious to the Hop in New York 



213 




Fig. 65. 



CHRYSALIS OF HOP MEKCH.-VNT. 
ABOUT NATURAL SIZE 

Polygonia inlerrogationis 



because of a superstition that is connected with them. If the spots on 
the chrysaUs (fig. 65) are golden, it is supposed that the hops will be of 
good quality and will bring a high 
price; but if the spots have a silver 
tint, the opposite is to be expected. 
Growers do not as a rule connect 
the spiny larva (figs. 66 and 67) or 
the brightly colored butterfly (fig. 68) 
of the two species with the hop mer- 
chant, and yet these insects have 
been of such popular interest to 
the student of nature that their life 
histories, food plants, and dimor- 
phism have been understood for 
many years. There are usually two broods a year, and the chrysalides of 

the second brood, 
often found at hop- 
picking time, are of 
great interest to 
hop pickers. The 
insects are not of 
economic impor- 
tance, for aside from 
a few leaves eaten 
by the larvae they 
do no harm. 

Many of the lar- 
vae of both species 
are parasitized by 
a bright green chal- 
cis fly {Pteromalus 
vanessae Hai'ris),'" 
The writer placed 
caterpillars of Pol- 
ygonia interrogationis in a cage in July, and when examined on August 
24 many of the chrysaUdes had taken on a distinctly yellow color and 

i» Determined by A. B. Gahan, thru the kindness of Dr. L. O. Howard. 




Fig. 66. 



LARVA OF HOP MERCHANT. ABOUT NATURAL SIZE 

Polygonia interrogationis 



214 



I. M. Hawlky 




Fig. (')7. i.arva of iioi' mickiiiam. nailkal bizii 
Polygonia inlcrrovatiov is 




Fig. 08. ADii.T OK Hor mkkc hant. si.i(;hti.y kkduced 

Polygania comma 

(Photcgtaph by H. H. KniRht) 



Insects Injurious to the Hop in New York 215 

parasites were found to be emerging thru holes in their sides. One 
chrysahs contained 12 full-grown chalcides. Howard (1897) believes the 
insects are held in check by this means. 

LEAF HOPPERS 

{Empoasca flavescens Fabricius and E. flavescens hirdii Coding) 

Leaf hoppers {Empoasca flavescens Fab. and the variety E. flavescens 
hirdii Coding) arc often present in large numbers on the hop plant. 
Twenty or more may be found on the underside of one of the lower leaves, 
but the insects are never found on the burs or the hops. The insect prob- 
ably winters as an adult in New York, since specimens have been found 
near yards and on hop poles during the first part of May of each year. 
In Illinois adults taken on December 16 emerged from hibernation on 
April 20 (Forbes, 1900). In 1915 nymphs of the first brood began to 
appear on the hop the middle of June; these transformed to adults about 
the middle of July, and from this time forward all stages could be found 
on the leaves. A second brood occurs every season, and in dry seasons 
there is probably a partial third brood. The insects seem to be more 
numerous in dry seasons. In 1913, when the hop aphis was scarce, there 
was a general outbreak of leaf hoppers. 

When leaf hoppers are numerous the leaves lack vitaUty and turn 
yellow. In June, 1915, in one badly infested yard the leaves were much 
curled. At that time the writer attributed the injury to leaf hoppers, 
but as this yard was frostbitten early in the season it is possible that this 
conclusion was incorrect. Accordingly an experiment was undertaken 
to test the point. Sevei-al hundred leaf hoppers were placed in paraffined 
bags which were tied on the arms of a hop vine in a yard nearly free from 
the insects. On July 14, over a month later, when the bags were exam- 
ined, the leaf hoppers were all dead and the leaves in one bag showed 
curling. In the other bags there was no curHng and the leaves appeared 
much as in the check bags. 

Empoasca flavescens is a general feeder. The writer has collected speci- 
mens on plum in the fall, and the variety hirdii has been previously 
reported on beans, weeds, walnuts, and apple trees (Forbes, 1900); in 
lUinois it often causes damage to the last-named host. E. flavescens hirdii 
has a smoky band across the hemelytra, which is wanting in E. flavescens. 



216 



I. M. Hawley 



The writer has taken both forms in the same hopyard. According to 
Forl)es (1900) the species is widespread; it has been reported from New 
York to the District of rohimbia. and from California and Mexico. 

CONTROL 

Wliile spraying for the red spider it was observed that flour paste often 
sticks the nymphs of leaf hoppers to the leaves. The usual aphis spray 
of nicotine sulfate and soap destroys them readily. 



THE MILLIPEDE 
(Julus caeruleocindus Wood) 

A species of millipede (Julun caeruleocindus,^^ fig. 69) seem-; to be always 
present in large numbers in hopyards. Several hundred specimens, in 

all stages of development, may often be 
taken from a single hill. They are the 
most plentiful where there is decaying | 
matter, and are especially numerous in 
dead antl dj'ing hop roots. 

No damage is caused by the milli- 
pede after the hop vines have become 
iiardened. In order to test this, a cage 
was sunk around a hop hill and several 
bundled millipedes were placed in it. " 
No damage to the vines resulted. In 
May, when the succulent hops are just 
coming up, shallow areas are occasionally eaten in the stems. These 
soon grow over without seriously retarding the growth of the vines. 

It was observed in the experiments for control of the hop grub. 
that carbon disulfid applied in large quantities often proved fatal to 

millipcd&s. 

THE LEAF MINER 

{Agromyza sp.) 
The larva of a dipterous leaf miner (Agromi/za sp.) is often found 
working in the lower leaves of the hop during May and June. On June 

1' Determined by R. V. Chaniberlin. 




Fig. G9. a millipkoe found in hop 

YARDS. X 2'. 



Insects Injurious to the Hop in New York 217 

7, 1915, the serpentine mines caused by the insects (fig. 70) were very 
numerous at Waterville. Specimens of the leaf miner were bred and 




Fig. 70. mine of a dipterous larva in a hop leaf, slightly enlarged 

identified for the writer by S. W. Frost. The insect belongs to the 
Agromyzidae and -is thought to be a new species. 

FLEA BEETLES 
(Psylliodes punctulata Melsh., and others) 

Flea beetles are occasionally found on the hop in New York, but they 
have never been numerous enough to cause serious damage. The writer 
has found from five to ten on a hill, and a lower leaf here and there will 
show the work of the insects in the form of small holes between the veins. 
In the hop sections of the Pacific coast, the hop flea beetle (Psylliodes 
punctulata) has caused great damage and has been a difficult pest to 
control (Parker, 1909). The following species have been taken by the 
writer on the hop plant: Psylliodes punctulata Melsh., the punctured 
flea beetle (the hop flea beetle of the Pacific coast); Epitrix cucumeris 



218 

Hair 
Fal).. 



I. M. Hawley 



i 



, till' i)()tat() flea beetle; Psylliodes convexior Lee; Sy.stena frontalis 
the rcd-heacled flea beetle. 



ina 



LEAF ROLLERS 
(Archips rosaceana Harris and A. argtjrospila Walker) 

The ol)lique-l)anded leaf roller (Archips rosaceana) is occasionally foiin 
on the hop. The white egg masses are found on the upper sitle of the 
leaf, and. are easily mistaken for a healthy spot of the hop mildew. An 
egg mass taken to the laboratory on July lo, 101'), hatched on July 18. 
Two of the larvae were separated and supplied with food. One pupated 
on August 15 and emerged on September 5; the other pupated on August 
17 and emerged on September 6. From other larvae taken to the labo- 
ratory, two parasites {Mcteorus sp. and Itoplectis conquisilor Say '-) were 
reared. The newly hatched larvae destroy a few leaves but do little 
real damage. 

A larva of the fruit-tree leaf roller (Archips argyrospila) was found on 
the hop on May 6, 1915. At that time it was feeding on the tender tissues 
of the tip, and hatl produced a muffle head similar to that caused by the 
larva of (lortyna inunanis. 

mSCELL.\NEOUS INSECTS ON HOP 
In the following list are given a number of additional species of in- 
sects that are found on hops, together with data regarding them. 



Species 


Stages 


Parts of 
plant infes'cj 


Time of 
appearance 


Numbers 


Injury 
caused 


Lygus pratengia Linn 

Lygus inrilus Say 


Nymph, adult 
Nvniph, adult. 

Adult 

Adult 

Adult 

Larva 

-Adult 

Adult 

Adult 

Larva 

Larva 

I.4irva 

Larva 

Larva 

Larva 

Larva 

Larva 


Lower leaves. . 
I.ower leaves. . 
Lower leaves. . 


July-August 

July-August 


Numerou."*. 
Ximierous. . 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 

Few 


None 
None 
None 


Diabrolica li- punctata Fab. 
Curymbitea cylindri/ormia 

Uerbst 

Lac iiDstenia hp 

Tel- phorua lubercuUUua Leo 
Tel plioruK bilinentits .Say 
Podiihrua rugoauJua Lee. . . . 

Mnmratr,! pirtn Harr 

I'eridroma margaritosa Haw 

Erannia tiliaria Harr 

Lyrin coqnaUirin CJucn 

A iilomeria io Fab 

Tropncn lunn Linn 

Sotii'upHwi anti'iiui Linn.. 
Hrmrrocampa leucoa'.igma 

Smith & Abbott 




None 


Hop heads, 
leaves 

Hoots 

Leaves 

Leaves 

I.«ave8 

I.«ave8 

Leaves 

Leaves 

Leaves 

I.«ave8 

I^eaves 

Iveaves 

Leaves 


May 


Slight 

None 
None 
None 
None 
Nono 


All seasons 

A ugust- September . 
.\ugast-September. 
A ugust-September. 




None 


May-June 


None 
None 


August-September 
Augu.st -Sept ember 
August -Sept ember. 
August-September. 


None 
None 
None 
None 



w Determined by A. B. Gahan, thru the kindness of Dr. L. O. Howard. 



. Insects Injurious to the Hop in New York 219 

BIBLIOGRAPHY 

(Hop-vine borer, or hop grub) 

Barnes, William, and McDunnough, J. Check list of the Lepidoptera 
of Boreal America, p. 1-392. (Reference on p. G9.) 1917. 
This is the latest work, and immanis is placed in the genus Gortyna. 

Bethune, C. J. S. Insects affecting the hop. Ent. Soc. Ontario. Ann. 
rept. 1872:27-34. (Reference on p. 33-34.) 1873. 

Detailed description of unidentified larva and brief description of its work; only 
the larval stage loiown. 

BEUTENMiJLLER, WiLLiAM. Gortyna immanis (Guen.). In Descriptive 

catalogue of the Noctuidae found within fifty miles of New York 

City. Part II. Amer. Mus. Nat. Hist. Bui. 16: 428-429. 1902. 
Detailed description of adult, which is mentioned as rare; illustration of adult. 

CoMSTOCK, J. H. The hop-vine borer, or hop grub. Amer. agr. 42: 75. 
1883. 

The first record that the hop grub is the species immanis. The egg is unknown, 
but the author thinks it is probably laid on the head of the hop, altho some eggs 
may be laid on the roots. Larvae found in May. Larva feeds on the head of 
the hop and bores down to the second joint, leaves the head, enters the vine, 
and later works externally. Pupa stage of one month begins in July or the first 
of August; no trace of cocoon or pupal cell. Author assumes hibernation of 
adult. Recommends control accoiding to Dodge. Article illustrated. 

Dodge, Charles R. The hop-vine borer. Can. ent. 14:93-96. {Re- 
■printedin Ent. Soc. Ontario, Ann. rept. 1882: 19-21. 1883.) 1882. 
First common name applied to insect; scientific name of insect unknown. Insect 
known in Wisconsin in 18G7. Loss of from 2.5 to .50 per cent of crop common. 
Life history similar to that given bj' other writers. Control: Apply salt, a handful 
to a hill; pinch heads containing larvae; hill early and remove dirt in May or June, 
and add a composite of salt, quicklime, and hen manure. Work of skunk men- 
tioned as controlling pest. 

Duckett, a. B. Para-dichlorobenzene as an insect fumigant. U. S. 

Dept. Agr. Bui. 167:1-7. 1915. 

Properties; use against insects found in stored grain. 

Dyar, Harrison G. A list of North American Lepidoptera and key to 
the literature of this order of insects. U. S. Nat. Mus. Bui. 52 : 1-723. 
(Reference on p. 175.) 1902. 

Edge, Thomas J. The hop-grub, or borer — Apamea Immanis. In 
Insect pests of the farm, garden, and orchard complained of in 1884. 
Pennsylvania State Bd. Agr. Ann. rept. 8(1884) : 105-106. 1885. 



220 I. M. Hawley 

Edwards, Hexuy. Apamca iininanis (luon. In BiblioKraphioal cata- 
logue of the described transformations of North American Lepi- 

doptera. U. S. Nat. Mus. Bui. 35:89. 1889. 
Two references for Apamea immanis. 

Fletcher, James. Notes on injurious insects in Canada in 1892. Insect 

life 5:124-127. 1892. 

Mention of Gortyna immanis. A parasite, Ichneumon subdnlus, has been bred from 
the pupae. 

The hop-vino ])orcr, " the collar-worm of the hop." In 



i 



Report of the Entomologist and Botanist. Canada Exp. Farms. 
Kept. 1892:149-1:31. 1893 a. 

Review of literature. Lif<» history of insect similar to that given by other writers; 
pupa state from fiv'e to seven weeks in Canada; wintering as adults assumed, since 
adults hide beneath rubbish on emerging. In addition to previously known 
control measures, the use of fish washed up on shore, applied around hills in heavy 
soils in spring, is said to work well. 

The 1892 report oi the official entomologist of Canada. 



Insect life 5:289. 1893 1). 

Mention of Hydroccia itnmanis. 

Flint, Daniel. The enemies of the hop plant. Pacific rural press, 
March 1882, p. 196. 1882. 

A popular article concerning an unknown insect which bores in hop vines and also 
in hop poles. [This has been reported by some WTiters to be Gortyna immanin, 
but is probably a beetle larva.) 

Grote, Aug. R. Hydroecia, Gortyna. In List of the Noctuidae of North 

America. Buffalo Soc. Nat. Sci. Bui. 2:18-19. 1874. 

A systematic paper. The type of Hydroecia is given as niclilans, and the type of 
Gortyna as micacea. The species immanis is in Gortyna. 

Gortyna obliqua Harvey. In North American moths, with 



I 



a preliminary catalogue of the species of Hadcna and Polia. U. S. 

Geol. and Geog. Survey Terr. Bui. 6:2()8. 1881. 

Author has no doubt of the specific validity of obliqua, which is considered by some 
authorities as a Western variety of immanis. 

GuENEE, A. Hydroecia Immanis. In Histoire naturclle des insectes. 

Lcpidopteres 5, Noctu6Utes i : 128-129. 1852. 
Original de.scription. 

Hampson, Sir George F, Hydroecia immanis. In Catalogue of the 

Lepidoptera Phalaenae in the British Museum 9:41. 1910. 
Description of adult of Hydroecia immanis; colored figure. 



Insects Injurious to the Hop in New York '221 

Harvey, Leon F. Gortyna obliqua, n. s. In New Californian and Texan 
moths. Can. ent. 8:53-54. 1876. 

Gortyna obliqua considered as a Western form of G. immanis. 

Holland, W. J. Genus Gortyna Ochsenheimer. In The moth book, 
p. 212-213. 1903. 

A brief discussion, with figures copied from Howard; colored figure of female. 

Howard, L. 0. The hop-plant borei-. In Some insects affecting the hop 
plant. U. S. Div. Ent. Bui. 7:40-44. 1897. 

A history of previous writings. Distribution given as Canada, New England, New 
York, and west to Washington; no injury to hops in Washington. Life history 
after that of former workers. Skunk often kills off many grubs. Recommenda- 
tions for control according to Smith. 

Pests of the hop crop. In The hop (H. Myrick, ed.), p. 



128-130. 1909. . 
A brief discussion. 

Lintner, J. A. Remedies for insect depredations. New York State 

Ent. First annual report on the injurious and other insects of the 

State of New York, p. 56-63. (Reference on p. 61.) 1882. 
Mention of skunk as attacking grub that works on hop root. 

The hop grub — Gortyna immanis (Guen.). New York 

State Ent. Second report on the injurious and other insects of the 
State of New York, p. 41-42. 1885. 

A history of previous writings. Life history compiled from other som-ces. List 
of collections of moths, with date, locality, and name of collector. 

(Jortyna immanis (Guenco). New York State Ent. Tenth 



report on the injurious and other insects of the State of New York, 

p. 372-373. 1895. 

Correspondence quoted, and control given after previous work. 

O'Kane, Walter C. The hop-plant borer (Hydroecia immanis Grt.). 
In Injurious insects, p. 136-137. 1912. 

Brief life history. Control: Pinch tips; remove dirt to drive the grubs deeper, 
and then apply ashes. 

Sanderson, E, Dwight. The hop-plant ])orer. In Insect pests of farm, 

garden, and orchard, p. 273-275. 1912, 
Account and illustrations taken from Howard. 

Smith, John B. The hop grub. In Report upon cranberry and hop 
insects. U. S. Div. Ent. Bui. 4 o. s. : 34-39. 1884. 

Author states that egg is laid on tip of hop vine as it begin.s to climb, and gives a 
description taken from growers' reports. [This egg is probably that of Hypena 



222 I. M. Hawley 

humnli.] Larva on hatchiiiK (Miti-rs head (»f hop and rausos head to hang down, 
forming a muffle head. Wlu'ti larva is one-half inch Idiik it Jeaves head and 
entt-rs vine, which iKcoines hard and hollow lus (low of sap stops. About .June 21 
larva leaves head and feeds on outside of vine, nearly or entire^ly severing it. 
Pupation occurs about the middle of .July in a rude cell; the pupae hilx-rnate 
as a rule, but a few adults emerge in the fall. Control: Cultivate skunks; de.stroy 
pupae in spring; pinch heads of hops; expose roots about one week in .June and 
add a mixture of coiil and wood ashes or ammoniated phosphate, then hill high, 
and vines stimulated by fertilizer will st^nd out rootlets to get food. Calomma 
calidum is predacious on young grubs. Hydroeda obliqua considered a Western 
variation of H. immanis. 

Hydroecia immanis Gn. /// Insoct.s of Now Jersey, p. 415. 



1890. 

Hydroecia immanis local in northern parts of State, the larva in the crown roots 
of hops. Times of flights, August and September. 

H. immanis On. In A cataloRuo, biographical and synonym- 



ical, of the species of moths of the lepidopterous superfamily Xoc- 

tuidae, found in Boreal America. U. S. Nat. Mas. Bui. 44:175. 

1893. 

A good bibliography. Distribution of insect given as northern United States from 
Atlantic to Pacific, New York in Augu.st, Wsishington, Colorado, and Illinois 
in August and September. Hydroecia ohliqua considered the same species as H. 



immanis. 



Hydroecia immanis Gn. In Revision of the genus Hydroecia 

Gn. Amer. Ent. Soc. Trans. 26:21. 1899. 

Bibliography. Detailed description of adult. Habitat. Hydroecia immanU said 
to resemble //. micacva. Discussion of genera Hydroecia and Gortyna found 
in the work. 

Hydroecia immanis Gn. In Insects of New Jersey, 2d ed., 

p. 415. 1900. 

Same as first edition (1890). 

Hydroecia immanis Gn. In In.sects of New Jersey, 3d ed., 

p. 4()2. 1910. 

Same as second edition (1900). 

Walker, Francis. Hydroecia immanis. In List of the specimens of 

lepidopterous insects in the collection of the British Museum 9:lG2. 

1856. 

Description of adult. 



Insects Injurious to the Hop in New York 223 

LITERATURE CITED 

(Hop redbug) 

McAtee, W. L. Key to the Nearctic species of Paracalocoris. (Heter- 
optera; Miridae.) Ent. Soc. Amer. Ann. 9:3(36-390. (Reference 
on p. 377-380.) 1916. 

Theobald, F. V. Notes on the needle-nosed hop bugs. South-Eaitern 
Agr. CoU. [Wye]. Joiirn. 2:11-16. 1895. 

(Hop snout-moth) 

Howard, L. 0. The hop-vine snout-moth. In Some insects affecting 
the hop plant. U. S. Div. Ent. Bui. 7:44-47. 1897. 

(Filamented looper) 

French, G. H. Nematocampa filamentaria Gue. — The strawberry 
geometer. In Economic entomology of Illinois, Part II, Lepidop- 
tera, p. 242-243. Seventh report of the State Entomologist on \\\2 
noxious and beneficial insects of the State of Illinois. Printed with 
Illinois Dept. Agr., Trans. 15. 1878. 

Lugger, Otto. The thread-bearing span-worm. In Butterflies and 
moths injurious to our fruit-producing plants. Minnesota Agr. 
Exp. Sta. Bui. 61:234-235. 1898. 

Packard, A. S. Nematocampa filamentaria Guenee. In A monograph 
of the geometrid moths or Phalaenidae of the United States. U. S. 
Geol. Survey Terr. Kept. 10: 471-472. 1876. 

(Hop aphis) 

Clarke, Warren T. The hop aphis. Univ. California Agr. Exp. Sta. 
Bui. 160:1-13. ,1904. 

Parker, William B. The hop aphis in the Pacific region. U. S. Bur. 

Ent. Bui. 111:1-39. 1913. 
Riley, C. V., and Alwood, W. B. The hop plant-louse. In Report of 

the Entomologist. U. S. Comm. Agr. Rept. 1888: 93-1 11. 1889. 



224 I M llwvLKV 

(Rod spider, or spider mite) 

Pahkkh, William B. VUmv piiste a.s a control for red spiders and as a 
spreader for eontaet insecticides. U. S. Hiir. Ent. Circ, 166:1-5. 
1913 a. 

The re<l spid(>r on hops in the SacrMiin'iito N'allcy «jf Cali- 
fornia. U. S. Bur. lOiit. Bill. 117: 1 11. P.H.il). 

(Hop merchants) 

HowAun, L. (). Hop merchants. In Some in.sects affecting the hop 
plant, r. S. Div. Hut. Bill. 7:47-51. 1S97. 

(Ix^if hoppers) 

F011BE.S, S. A. Emixjasca flavescens Fal)r. In The economic entomology 
of the sugar Ix'ct. Illinois Agr. Exp. Sla. Bui. 00:427. 19(X). 

(Flea Ixictlcs) 

l'\i{Ki:i{. William B. The life history and control of the hop flea-beetle. 
In Soine in.sects injurious to truck crops. U. S. Bur. Ent. Bui. 
82:33-58. 1909. 

.Mfinoir 13, Chlorophfll I nhrritancc in Maize, the second precedinK number iu this scries of publications, 
naanuu!(!(i on August 31, 10 is. 



